A complex life form has been found living 1 mile below the Earth's surface, according to a study published in the journal Nature, proving life can thrive in a place where only bacteria were thought to exist. Nicknamed "worms from hell," the newly discovered nematodes (pictured) were found living in several South African gold mines, shattering scientific assumptions about the conditions needed for multicellular life. To find animals with nervous, digestive and reproductive systems so deep underground is like finding "Moby Dick in Lake Ontario," study co-author Tullis Onsott of Princeton University tells the Washington Post. "This is telling us something brand new," he says. "For a relatively complex creature like a nematode to penetrate that deep is simply remarkable."
Nematodes, aka roundworms, are known to exist on the deep ocean floor, but they're typically not found more than 10 to 20 feet underneath the ground or the seabed, says co-author Gaetan Borgonie from Belgium's University of Ghent. Yet Borgonie saw no reason they couldn't survive deeper than that, and without funding or professional support, he contacted Onsott with an idea to search for nematodes in boreholes below gold mines. "Everyone thought I was insane risking a career hunting something everybody said they knew could not be," Borgonie tells Wired. But the duo ended up finding the elusive nematodes, formally named Halicephalobus mephisto, living in extremely hot water fed by subterranean rock fissures and pools — essentially "uncovering a new realm of biology on Earth," the Post reports.
Beyond some big implications for our own biosphere — potentially offering insight about the origins of life on Earth, or at least broadening the horizons of where it might exist — the discovery could also open new doors for the study of alien life, known as astrobiology. If complex worms can live a mile below the Earth's surface, it seems more plausible that some sort of life could survive under the surface of Mars, for example. "What we found shows that harsh conditions do not necessarily exclude complexity," Borgonie says, adding that "evolution of Martian life might have continued underground. ... Life on Mars could be more complex than we imagined."