In the crushing darkness nearly 10,000 meters below the surface, where the ocean pressure would crush a human body in seconds, scientists have discovered an entirely unexpected city of life clinging to bare rock. Led by researchers at China's Institute of Deep-Sea Science and Engineering, an international team publishing in Science on May 14 has revealed a thriving community of 32 previously unknown species living on hard substrates across seven hadal trenches in Oceania—a finding that rewrites what we thought we knew about how life survives in the planet's most extreme environment.
The hadal zone, those deepest ocean trenches plunging between 6,000 and nearly 11,000 meters, has long been treated as a frontier of ignorance. Rock samples from these extreme depths had been nearly impossible to recover, leaving entire ecosystems hidden from scientific view. But using 98 dives of the manned submersible Fendouzhe—China's full-ocean-depth research vessel—Dr. Song Xikun, Dr. Peng Xiaotong, and their collaborators finally pierced that veil. They documented fauna across the Kermadec and Mariana trenches, at depths reaching 10,898 meters, revealing a universe of millimeter-sized organisms so densely packed they reach 4,300 individuals per cubic decimeter.
What makes this discovery revolutionary is not just the species count but what these organisms actually are and how they survive. The dominant life forms are agglutinated foraminifera—known locally in Chinese as "rock feathers" or shirong—tiny creatures that for years had been invisible to science because their small size and simple appearance made DNA extraction nearly impossible. They belong to six different phyla, including a brand-new bryozoan family named Pierrellidae and a new foraminiferal family called Plumettidae. Several species have shattered depth records: the deepest known bryozoan ever recorded (Pierrella fendouzhei, at 9,981 meters), scyphozoan polyps (9,982 meters), and hydrozoan polyps (9,195 meters).
But the real surprise lies in how these creatures eat. Scientists found no chemosynthetic tubeworms or clams—the classic indicators of energy production in the deep sea. Instead, metagenomic analysis revealed something astonishing: these foraminifera are heterotrophs that feed on terrestrial pine pollen, often found in various stages of digestion in their bodies. Organic matter tumbles down the trench walls through turbidity currents, and these tiny creatures have evolved to hang downward from rock crevices, positioning themselves to capture those precious particles while avoiding burial by sediment. It is elegance born of necessity in absolute darkness.
The ecological significance extends far beyond discovering a few new species. These small foraminifera contribute an estimated 2 to 11 percent of total eukaryotic biomass carbon in global hadal trenches—a previously overlooked carbon hotspot with major implications for how we understand deep-sea carbon cycling and the efficiency of the ocean's biological pump. Similar communities have now been found in five additional trenches worldwide (the Aleutian, Kuril-Kamchatka, Puysegur, Atacama, and Mussau), suggesting these hard-substrate communities may be far more common than anyone realized.
The discovery also hints at deeper mysteries. Some bryozoan lineages found in these trenches trace back to the Cretaceous period, suggesting the hadal zone may serve as a refuge for ancient species that elsewhere went extinct. As Dr. Peng's international team—spanning Earth Science New Zealand, the UK's National Oceanography Centre, institutions in Germany, Austria, Indonesia, and leading Chinese universities—prepares the next phase of exploration under the Global Hadal Exploration Program, the questions only multiply. How are these communities connected globally? What other ancient lineages hide in the dark? In the deepest places on Earth, life keeps revealing that we know far less than we thought.