Glaucomaria

Glaucomaria is a genus of lichen-forming fungi in the family Lecanoraceae. Species in this genus have a crust-like growth form and are distinguished by their heavily powdery fruiting bodies, which produce a bright lemon-yellow colour when treated with bleach. The genus occurs on both tree bark and siliceous rock across most continents, though it is absent from Antarctica. All species produce the compounds sordidone and atranorin as their main secondary metabolites....read more on Wikipedia.