Rock Eaters

Chemolithoautotrophs are also known as "Rock eaters". They get their energy from the chemical reactions of inorganic minerals. Most species are aerobic (require Oxygen) and hence their ecology is directly linked to sunlight. Not all species require Oxygen and so their ecologies can exist in the complete absence of sunlight. They are specialised feeders, requiring a specific diet to survive. Because the yield of energy is so low they must oxidise a large quantity of inorganic material to grow and reproduce, and this magnifies their ecological impact.

Alcaligenes spp.H2, O2H2O
Pseudomonas spp.H2, O2H2O
Nitrobacter spp.NO2-, O2NO3-, H2O
Nitrosomonas spp.NH4+, O2NO2-, H2O
Thiobacillus denitrificansS0, H2S, NO3-SO42-, N2
Thiobacillus ferrooxidansFe2+, S0, H2S, O2Fe3+, H2SO4, H2O

Frozen surface planet
A planet that's frozen and inhospitable to life on the surface may be teeming with bacterial life underground. The core would need to be warm and liquid water available. The bacterial waste products must be recycled by geothermal energy, which is slow process. An ecology on this type of planet would be size limited.