Lithophiles are

micro-organism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s that can live within the pore interstices of

sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

and even fractured

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

rocks to depths of several kilometers. Some are known to live on surface rocks, and make use of

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

for energy. Those that live in deeper rocks cannot use

to gather energy, but instead extract energy from minerals around them. They live in cracks in the rock where water seeps down. The water contains dissolved

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

(CO₂) which the organisms use for their carbon needs. They have been detected in rocks down to depths of nearly three km, where the temperature is approximately 75 °C. Terrestrial lithophiles can be found in canyons primarily composed of

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

, an igneous rock, and soils saturated with fractured rock. Organisms from the genus ''Elliptochloris'', a subaerial photosynthetic green algae, demonstrate lithophilic preferences through colonization in granite cracks and in proximity to terrestrial lichens. Lithophilic lichens from the genus ''

Collema ''Collema'' (jelly lichen) is a genus of lichens in the family Collemataceae. The photobiont is the cyanobacterium genus ''Nostoc''.Dobson, F.S. (2000) Lichens, an illustrated guide to the British and Irish species. 4th edition. Richmond publish ...

'' form tight symbiotic relationships between fungi and photosynthetic algae such as ''Elliptochloris'' in order to produce necessary saturated fatty acid secondary metabolites. Lithophilic algal species colonizing fractured rock outcroppings individually exhibit coccal morphological shape while aggregating into an elliptical or globular arrangement during adulthood. Lithobiontic ecological niches further classify lithophiles into sub-categories determined by their spatial niche specificity. The term, lithic, refers to an association with rock and can be further explained by the term, lithobiontic, regarded as organisms living both on, and within rock surfaces. Sub-surface rock organisms, endoliths, primarily exhibit niche preference within fissures, cavities, or tunnels of various rocks. While many endoliths degrade and effectively excavate the available

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

rock surface, many are preyed upon by select gastropod, and

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

species. This habitat preference can be further threatened by suspension feeding organisms searching for acquired shelter.

References

{{Microbiology-stub