The existence of undiscovered strains of microbial lithoautotrophs is theorized based on some of these cycles, as they are needed to explain phenomena like the conversion of ammonium in iron-reducing environments. Lithoautotrophs may be present in the deep terrestrial subsurface (they have been found well over 3 km below the surface of the planet), in soils, and in endolith communities.
The existence of unknown strains of lithoautotrophic microorganisms is hypothesized based on some of these cycles, as they are necessary to explain occurrences such as ammonium conversion in iron-reducing environments. Lithoautotrophs might be present in the deep terrestrial subsurface (they have been discovered over 3 kilometers below the planet's surface), in soils, and within endolithic communities.