Diploicia canescens

Diploicia canescens is a widespread species of lichen-forming fungus in the family Caliciaceae. It is found throughout much of the world, occurring on every continent except Antarctica. It is a crustose lichen with distinctive lobed margins that grows in rosettes up to 6 cm (2.4 in) across, appearing white to pale gray with white-pruinose marginal lobes. The species contains various biologically active compounds including depsidones, depsides, and phthalides. It typically grows on rocks, old walls, and tree trunks, particularly favoring nutrient-enriched areas such as birds' perching stones, though it is sensitive to sulfur dioxide pollution. Two subspecies are recognized: D. c. canescens and D. c. australasica, which differ in their chemical composition. ...read more on Wikipedia.