Chaenotheca brachypoda

Chaenotheca brachypoda is a species of lichen in the family Coniocybaceae. This tiny pin lichen is almost invisible except for its minute fruiting structures that rise like microscopic pins from tree bark, each topped with a yellow-green, frost-like coating containing distinctive acids. Originally described in 1816 from specimens growing on pine logs in Sweden, it lives mostly hidden within the bark of its host tree, with only hair-fine stalks extending upward to release powdery spores from spherical heads barely 0.2 mm across....read more on Wikipedia.