A variety of terricolous fungi inhabit the biological soil crust of arid regions. Those exposed to the sun typically contain melanin

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

 and are resistant to high temperatures, dryness and low nutrition. Species that are common elsewhere (e.g. Penicillium

Penicillium

Penicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body...

 spp. and common soil Aspergillus

Aspergillus

Aspergillus is a genus consisting of several hundred mold species found in various climates worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli...

 spp.) do not thrive in these conditions. Producing large dark unicellular spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s also helps survival. Sexually reproducing ascomycetes, especially Chaetomium

Chaetomium

Chaetomium is a genus of fungi in the Chaetomiaceae family. It is a dematiaceous mold normally found in soil, air, and plant debris. According to the Dictionary of the Fungi , there are about 95 species in the widespread genus.As well as being a contaminant, Chaetomium spp. are also encountered as...

 spp., have developed resilience by growing thick, dark perithecia. Under desert shrubs, however, more sensitive species such as Gymnoascus reesii prevail.