There are microbes near the bottom of the third deepest hole in the world. The cells, recovered from rocks almost 5 kilometres below the surface of China, are the deepest cells so far found anywhere on land – and they may push beyond the known heat tolerances of life on Earth.

It is widely accepted that life exists at depth . Until now, the deepest known microbes on land were tiny nematode worms found 3.6 kilometres below the surface in a South African gold mine.

A …