Marine researchers exploring extreme depths say they have discovered an astonishing deep-sea ecosystem of chemosynthetic life that’s fueled by gases escaping from fractures in the ocean bed. The expedition revealed methane-producing microbes and marine invertebrates that make their home in unforgiving conditions where the sun’s rays don’t reach, according to a new study.

Geochemist Mengran Du had 30 minutes left in her submersible mission when she decided to explore one last stretch of the trenches that lie between Russia and Alaska, about 5,800 to 9,500 meters (19,000 to 30,000 feet) below the ocean’s surface in what’s called the hadal zone. She said she began to notice “amazing creatures,” including various species of clam and tube worm that had never been recorded so deep below the sur

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