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In the deepest parts of the Pacific Ocean, a glowing yellow worm has mastered survival in one of the most toxic places on Earth.

Bathed in arsenic and sulfide from hydrothermal vents, it neutralizes the poisons by transforming them into golden mineral crystals, turning deadly chemicals into glittering protection.

Poison-Resistant Worm Discovery

A deep-sea worm that lives around hydrothermal vents has evolved a remarkable survival trick: it combines two deadly substances, arsenic and sulfide, inside its cells to create a far less harmful mineral. The discovery, described by Chaolun Li of the Institute of Oceanology, CAS, China, and his colleagues, was published August 26th in the open-access journal PLOS Biology.

The species, known as Paralvinella hessleri, is the only animal that can withstand the hottest zones of deep-sea vents in the western Pacific. These vents gush out superheated, mineral-rich water containing high concentrations of sulfide and arsenic. Over time, the arsenic accumulates in the worm’s tissues, in some cases accounting for more than 1% of its total body weight.

Life in Extreme Deep-Sea Vents

To uncover how P. hessleri survives such a hostile environment, Li’s team used advanced microscopy along with DNA, protein, and chemical analysis. Their work revealed an entirely new detoxification process. The worm traps arsenic particles in its skin cells, where they interact with sulfide from the vent fluids to form clusters of a bright yellow mineral called orpiment.

This unusual process sheds light on a strategy that researchers describe as “fighting poison with poison.” It allows the worm to live in an environment that should be lethally toxic. Other studies suggest that some closely related worm species and certain snails in the western Pacific also build up large amounts of arsenic and may rely on a similar adaptation.

Fighting Poison With Poison

Coauthor Dr. Hao Wang adds, “This was my first deep-sea expedition, and I was stunned by what I saw on the ROV monitor—the bright yellow Paralvinella hessleri worms were unlike anything I had ever seen, standing out vividly against the white biofilm and dark hydrothermal vent landscape. It was hard to believe that any animal could survive, let alone thrive, in such an extreme and toxic environment.”

Dr. Wang says, “What makes this finding even more fascinating is that orpiment—the same toxic, golden mineral produced by this worm—was once prized by medieval and Renaissance painters. It’s a curious convergence of biology and art history, unfolding in the depths of the ocean.”

A Strange Link to Art History

The authors note, “We were puzzled for a long time by the nature of the yellow intracellular granules, which had a vibrant color and nearly perfect spherical shape. It took us a combination of microscopy, spectroscopy, and Raman analysis to identify them as orpiment minerals—a surprising finding.”

The authors conclude, “We hope that this ‘fighting poison with poison’ model will encourage scientists to rethink how marine invertebrates interact with and possibly harness toxic elements in their environment.”

Reference: “A deep-sea hydrothermal vent worm detoxifies arsenic and sulfur by intracellular biomineralization of orpiment (As2S3)” by Hao Wang, Lei Cao, Huan Zhang, Zhaoshan Zhong, Li Zhou, Chao Lian, Xiaocheng Wang, Hao Chen, Minxiao Wang, Xin Zhang and Chaolun Li, 26 August 2025, PLOS Biology.
DOI: 10.1371/journal.pbio.3003291

Funding: This work was supported by grants from Natural Science Foundation of China (No. 42476133 to H.W.), Science and Technology Innovation Project of Laoshan Laboratory (Project Number No. LSKJ202203104 to H.W.), National Key RandD Program of China (Project Number 2018YFC0310702 to H.W.), Natural Science Foundation of China (Grant No. 42030407 to C.Li), and the NSFC Innovative Group Grant (No. 42221005 to M.X.W.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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The inside of Mars isn’t smooth and uniform like familiar textbook illustrations. Instead, new research reveals it’s chunky — more like a Rocky Road brownie than a neat slice of Millionaire’s Shortbread.

We often picture rocky planets like Earth and Mars as having smooth, layered interiors — with crust, mantle, and core stacked like the biscuit base, caramel middle, and chocolate topping of a millionaire’s shortbread. But the reality for Mars is rather less tidy.

Seismic vibrations detected by NASA’s InSight mission revealed subtle anomalies, which led scientists from Imperial College London and other institutions to uncover a messier reality: Mars’s mantle contains ancient fragments up to 4km wide from its formation — preserved like geological fossils from the planet’s violent early history.

History of gigantic impacts

Mars and the other rocky planets formed about 4.5 billion years ago, as dust and rock orbiting the young Sun gradually clumped together under gravity.

Once Mars had largely taken shape, it was struck by giant, planet-sized objects in a series of near-cataclysmic collisions — the kind that also likely formed Earth’s Moon.

“These colossal impacts unleashed enough energy to melt large parts of the young planet into vast magma oceans,” said lead researcher Dr Constantinos Charalambous from the Department of Electrical and Electronic Engineering at Imperial College London. “As those magma oceans cooled and crystallised, they left behind compositionally distinct chunks of material — and we believe it’s these we’re now detecting deep inside Mars.”

These early impacts and their aftermath scattered and mixed fragments of the planet’s early crust and mantle — and possibly debris from the impacting objects themselves — into the molten interior. As Mars slowly cooled, these chemically diverse chunks were trapped in a sluggishly churning mantle, like ingredients folded into a Rocky Road brownie mix, and the mixing was too weak to fully smooth things out.

Unlike Earth, where plate tectonics continuously recycle the crust and mantle, Mars sealed up early beneath a stagnant outer crust, preserving its interior as a geological time capsule.

“Most of this chaos likely unfolded in Mars’s first 100 million years,” says Dr Charalambous. “The fact that we can still detect its traces after four and a half billion years shows just how sluggishly Mars’s interior has been churning ever since.”

Listening into Mars

The evidence comes from seismic data recorded by NASA’s InSight lander — in particular, eight especially clear marsquakes, including two triggered by two recent meteorite impacts that left 150-metre-wide craters in Mars’s surface.

InSight picks up seismic waves travelling through the mantle and the scientists could see that waves of higher frequencies took longer to reach its sensors from the impact site. These signs of interference, they say, shows that the interior is chunky rather than smooth.

“These signals showed clear signs of interference as they travelled through Mars’s deep interior,” said Dr Charalambous. “That’s consistent with a mantle full of structures of different compositional origins — leftovers from Mars’s early days.”

“What happened on Mars is that, after those early events, the surface solidified into a stagnant lid,” he explained. “It sealed off the mantle beneath, locking in those ancient chaotic features — like a planetary time capsule.”

Unlike the interior of Earth

Earth’s crust, by comparison, is always slowly shifting and recycling material from the surface into our planet’s mantle – at tectonic plates such as the Cascadia subduction zone where some of the plates forming the Pacific Ocean floor are pushed under the North American continental plate.

The chunks detected in Mars’s mantle follow a striking pattern, with a few large fragments — up to 4 km wide — surrounded by many smaller ones.

Professor Tom Pike, who worked with Dr Charalambous to unravel what caused these chunks, said: “What we are seeing is a ‘fractal’ distribution, which happens when the energy from a cataclysmic collision overwhelms the strength of an object. You see the same effect when a glass falls onto a tiled floor as when a meteorite collides with a planet: it breaks into a few big shards and a large number of smaller pieces. It’s remarkable that we can still detect this distribution today.”

The finding could have implications for our understanding of how the other rocky planets — like Venus and Mercury — evolved over billions of years. This new discovery of Mars’s preserved interior offers a rare glimpse into what might lie hidden beneath the surface of stagnant worlds.

“InSight’s data continues to reshape how we think about the formation of rocky planets, and Mars in particular,” said Dr Mark Panning of NASA’s Jet Propulsion Laboratory in Southern California. JPL led the InSight mission before its end in 2022. “It’s exciting to see scientists making new discoveries with the quakes we detected!”

“These mysterious objects are candidate galaxies in the early universe, meaning they could be very early galaxies,” said Haojing Yan, an astronomy professor in Mizzou’s College of Arts and Science and co-author on the study. “If even a few of these objects turn out to be what we think they are, our discovery could challenge current ideas about how galaxies formed in the early universe — the period when the first stars and galaxies began to take shape.”

But identifying objects in space doesn’t happen in an instant. It takes a careful step-by-step process to confirm their nature, combining advanced technology, detailed analysis and a bit of cosmic detective work.

Step 1: Spotting the first clues

Mizzou’s researchers started by using two of JWST’s powerful infrared cameras: the Near-Infrared Camera and the Mid-Infrared Instrument. Both are specifically designed to detect light from the most distant places in space, which is key when studying the early universe.

Why infrared? Because the farther away an object is, the longer its light has been traveling to reach us.

“As the light from these early galaxies travels through space, it stretches into longer wavelengths — shifting from visible light into infrared,” Yan said. “This stretching is called redshift, and it helps us figure out how far away these galaxies are. The higher the redshift, the farther away the galaxy is from us on Earth, and the closer it is to the beginning of the universe.”

Step 2: The ‘dropout’

To identify each of the 300 early galaxy candidates, Mizzou’s researchers used an established method called the dropout technique.

“It detects high-redshift galaxies by looking for objects that appear in redder wavelengths but vanish in bluer ones — a sign that their light has traveled across vast distances and time,” said Bangzheng “Tom” Sun, a Ph.D. student working with Yan and the lead author of the study. “This phenomenon is indicative of the ‘Lyman Break,’ a spectral feature caused by the absorption of ultraviolet light by neutral hydrogen. As redshift increases, this signature shifts to redder wavelengths.”

Step 3: Estimating the details

While the dropout technique identifies each of the galaxy candidates, the next step is to check whether they could be at “very” high redshifts, Yan said.

“Ideally this would be done using spectroscopy, a technique that spreads light across different wavelengths to identify signatures that would allow an accurate redshift determination,” he said.

But when full spectroscopic data is unavailable, researchers can use a technique called spectral energy distribution fitting. This method gave Sun and Yan a baseline to estimate the redshifts of their galaxy candidates — along with other properties such as age and mass.

In the past, scientists often thought these extremely bright objects weren’t early galaxies, but something else that mimicked them. However, based on their findings, Sun and Yan believe these objects deserve a closer look — and shouldn’t be so quickly ruled out.

“Even if only a few of these objects are confirmed to be in the early universe, they will force us to modify the existing theories of galaxy formation,” Yan said.

Step 4: The final answer

The final test will use spectroscopy — the gold standard — to confirm the team’s findings.

Spectroscopy breaks light into different wavelengths, like how a prism splits light into a rainbow of colors. Scientists use this technique to reveal a galaxy’s unique fingerprint, which can tell them how old the galaxy is, how it formed and what it’s made of.

“One of our objects is already confirmed by spectroscopy to be an early galaxy,” Sun said. “But this object alone is not enough. We will need to make additional confirmations to say for certain whether current theories are being challenged.”

The study, “On the very bright dropouts selected using the James Webb Space Telescope NIRCam instrument,” was published in The Astrophysical Journal.

“Unlike most nearby planet-forming disks, where water vapor dominates the inner regions, this disk is surprisingly rich in carbon dioxide,” says Jenny Frediani, PhD student at the Department of Astronomy, Stockholm University.

“In fact, water is so scarce in this system that it’s barely detectable — a dramatic contrast to what we typically observe.”

A newly formed star is initially deeply embedded in the gas cloud from which it was formed and creates a disk around itself where planets in turn can be formed. In conventional models of planet formation, pebbles rich in water ice drift from the cold outer disk toward the warmer inner regions, where the rising temperatures cause the ices to sublimate. This process usually results in strong water vapor signatures in the disk’s inner zones. However, in this case, the JWST/MIRI spectrum shows a puzzlingly strong carbon dioxide signature instead.

“This challenges current models of disk chemistry and evolution since the high carbon dioxide levels relative to water cannot be easily explained by standard disk evolution processes,” Jenny Frediani explains.

Arjan Bik, researcher at the Department of Astronomy, Stockholm University, adds, “Such a high abundance of carbon dioxide in the planet-forming zone is unexpected. It points to the possibility that intense ultraviolet radiation — either from the host star or neighbouring massive stars — is reshaping the chemistry of the disk.”

The researchers also detected rare isotopic variants of carbon dioxide, enriched in either carbon-13 or the oxygen isotopes ¹⁷O and ¹⁸O, clearly visible in the JWST data. These isotopologues could offer vital clues to long-standing questions about the unusual isotopic fingerprints found in meteorites and comets — relics of our own Solar System’s formation.

This CO2-rich disk was found in the massive star-forming region NGC 6357, located approximately 1.7 kiloparsecs (about 53 quadrillion kilometers) away. The discovery was made by the eXtreme Ultraviolet Environments (XUE) collaboration, which focuses on how intense radiation fields impact disk chemistry.

Maria-Claudia Ramirez-Tannus from the Max Planck Institute for Astronomy in Heidelberg and lead of the XUE collaboration says that it is an exciting discovery: “It reveals how extreme radiation environments — common in massive star-forming regions — can alter the building blocks of planets. Since most stars and likely most planets form in such regions, understanding these effects is essential for grasping the diversity of planetary atmospheres and their habitability potential.”

Thanks to JWST’s MIRI instrument, astronomers can now observe distant, dust-enshrouded disks with unprecedented detail at infrared wavelengths — providing critical insights into the physical and chemical conditions that govern planet formation. By comparing these intense environments with quieter, more isolated regions, researchers are uncovering the environmental diversity that shapes emerging planetary systems. Astronomers at Stockholm University and Chalmers have helped develop the MIRI instrument which is a camera and a spectrograph that observes mid- to long-wavelength infrared radiation from 5 microns to 28 microns. It also has coronagraphs, specifically designed to observe exoplanets.

The study “XUE: The CO2-rich terrestrial planet-forming region of an externally irradiated Herbig disk” is published in Astronomy & Astrophysics.