Japan - August 25, 2025 West Pacific Ocean – A deep sea worm, Paralvinella hessleri, has been discovered surviving in the hottest, most toxic parts of hydrothermal vents by converting deadly arsenic and sulfide into a less hazardous mineral. Researchers from the Institute of Oceanology, CAS, China, report that the worm accumulates arsenic in its skin cells, which then reacts with sulfide from the vent fluids to form tiny clumps of yellow mineral called orpiment. This unique detoxification allows P. hessleri to thrive where no other animals can. The worm inhabits hydrothermal vents where mineral-rich water spews from the seafloor. Arsenic can make up more than 1% of the worm’s body weight. Using advanced microscopy and chemical analyses, scientists uncovered this previously unknown survival strategy. Dr. Hao Wang, coauthor of the study, said, “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.” The study also notes the curious link to human history: orpiment, produced by the worms, was once prized by medieval and Renaissance painters for its golden pigment. Researchers hope this “fighting poison with poison” mechanism will inspire new understanding of how marine invertebrates interact with toxic elements in extreme environments.