Autotrophs were found in a rock called basalt, an igneous rock. An igneous rock is one that was consolidated from a molten state, formed from the action of great heat within the earth. Once a new rock has cooled, groundwater will carry the bacteria to the sterile zones. This process is very slow because the organisms can not travel downward from the surface faster than the groundwater. This means that some of the communities of organisms below the surface have to be at least several million years old.
Some bacteria survive because the nutrients are always being recycled.
But most types of bacteria shrink as their stores are being used up. These types are called dwarf bacteria, founded by Thomas L. Kieft from the New Mexico Institute of Mining and Technology. There have been more than 9000 kinds of subsurface microorganisms catalogued and preserved. All of these experiments have given scientists a better understanding of how life can exist in isolation from the surface. It may also indicate how life functioned on the early earth and it may also lead us to believe that extraterrestrials do exist.