The Integrated Ocean Drilling Program sank its drill into the Atlantis Massif in the central Atlantic Ocean where seismic forces have pushed the deep layer, known as the gabbroic layer, to within 230 feet of the ocean floor making it easier to reach, NewScientist.com reported.
A team from Oregon State University drilled down to 4,500 feet, where temperatures reach 215 degrees Fahrenheit.
At that depth, they found widespread communities of bacteria, Stephen Giovannoni of OSU said.
Many of the bacteria discovered have evolved to feed off hydrocarbons like methane and benzene, similar to the bacteria found in oil reservoirs, he said.
"This deep biosphere is a very important discovery," said Rolf Pedersen of the University of Bergen in Norway.
Reactions that produce oil and gas inside the crust could happen in the mantle, he says, meaning life may be thriving deeper yet.