Granite moss, also called rock moss, any of the plants of the order Andreaeales of the subclass Andreaeidae, comprising a single family, Andreaeaceae, which includes the genus Andreaea, with fewer than 100 species, including A. fuegiana, which formerly made up the separate genus of Neuroloma. The reddish brown or blackish plants are about 2 cm (0.8 inch) high and grow in cold climates on nonlimy rocks such as granite or slate outcroppings.
(https://www.britannica.com/plant/granite-moss)