Deep biosphere

Life in the deep subsurface of the Earth

The deep biosphere is the part of the biosphere that resides below the first few meters of the surface. It extends down below 10 kilometers below the continental surface and 21 kilometers below the sea surface, at temperatures that may reach beyond 120 °C (248 °F) which is comparable to the maximum temperature where a metabolically active organism has been found. It includes all three domains of life and the genetic diversity rivals that on the surface.

This keyword could refer to multiple things. Here are some suggestions: