Candelariella efflorescens

Candelariella efflorescens, commonly known as the powdery goldfleck lichen, is a sorediate, corticolous (bark-dwelling) crustose lichen in the family Candelariaceae. It is widespread in temperate parts of North America and Europe and has also been confirmed from Asia (Pakistan) by DNA sequence data. The thallus consists of minute yellow areoles that quickly "effloresce" into fine yellow soredia to form a continuous powdery crust; fruiting bodies (apothecia) are rare and small. When fertile, the species has multispored asci (typically 24–30 ascospores), a character separating it from several superficially similar eight-spored species now recognised alongside it....read more on Wikipedia.