Which creature lives the deepest underground?

The deepest dwelling land animal is a kind of springtail called Plutomurus ortobalaganensis (pictured). It was first discovered in the world’s deepest cave in Abkhazia near the Black Sea, at a depth of 1,980 metres (6,500 feet). This wingless and eyeless insect lives in total darkness in temperatures just above freezing and feeds on fungi. But even deeper than that is a roundworm half a millimetre long called Halicephalobus mephisto that lives in the water that seeps into cracks in the rock. This has been found at the bottom of a South African gold mine, living in rocks 3.6 kilometres (2.2 miles) below the surface!