Rather, energy was extracted by chemoautotrophic bacteria, living in a film on top of the water of an underground lake. These bacteria produce energy by oxidizing the sulfide compounds in the water, and derive organic compounds using carbon dioxide from the air.
Instead of photosynthesis, energy extraction occurred through chemoautotrophic bacteria living on top of the water layer within an underground lake. These bacteria oxidize sulfide compounds to generate energy and produce organic compounds with the help of atmospheric carbon dioxide.