Psora cerebriformis
Brain scale lichen
This squamulose lichen has a thallus made up of cracked, rounded, 8 mm wide scales which grow in tight patches over patches of soil in desert regions of western North America. These lichens do what a lot of terricolous lichens do really well, and that is to hold soil in place and prevent erosion. When the soil around them erodes away, it often leaves behind domed patches covered in wrinkled scales which look surprisingly brain-like. The upper surface of these scales is gray to olive in color, and often covered in a thick layer of chalky, whitish-gray pruina. The lower surface is typically pale brown to white. P. cerebriformis produces bulbous, black apothecia along the margins of the scales, though they are often obscured by pruina and blend in with the rest of the upper surface.
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