Pseudopeltula necrocorticata

Pseudopeltula necrocorticata is a species of cyanolichen in the family Lichinaceae. It forms small, yellowish-olive, scale-like lobes up to about 3.5 mm across on rock and gravel in desert habitats. The species is unusual in having a surface layer formed partly from dead cyanobacterial cells, which gives rise to its name. It is known from the Sonoran Desert region of northwestern Mexico, where it may be overlooked because it resembles small species of Peltula....read more on Wikipedia.