ananyo writes "A newly-discovered microbial community living tens of meters beneath the Pacific Ocean floor uses so little oxygen that researchers believe they may be living at the absolute minimum energy requirement needed to subsist. For years, scientists thought that the ascetic conditions of the deep sub-seabed — high pressure, minimal oxygen and a low supply of nutrients and energy — made such environments uninhabitable to any form of life. The discovery extends the lower bound for life (abstract). The surface of Mars, for instance, may be inhospitable, but there may be conditions below the surface that are reminiscent of the deep subsurface on Earth. As microbiologist Bo Jørgensen comments in the Nature piece, while the discovery does not mean there is life on Mars, 'it's now really challenging to show where there is no life.'"