Chrysothrix candelaris

About

Chrysothrix candelaris, commonly known as the mustard powder lichen or gold dust lichen, is a species of leprose (powdery) lichen in the family Chrysothricaceae. It typically grows on tree bark, although it has also been recorded growing on rock. It does not show ascocarps or other reproductive structures, belonging to the group commonly known as the 'Fungi or lichens imperfecti' in the UK.

Summary from Wikipedia