Myriostoma is a fungal genus in the family Geastraceae. The genus is has four species, with the type species being Myriostoma coliforme. It is an earthstar, so named because the spore-bearing sac's outer wall splits open into the shape of a star. The inedible fungus has a cosmopolitan distribution, and has been found in Africa, Asia, North and South America, and Europe, where it grows in humus-rich forests or in woodlands, especially on well-drained and sandy soils. A somewhat rare fungus, it appears on the Red Lists of 12 European countries, and in 2004 it was one of 33 species proposed for protection under the Bern Convention by the European Council for Conservation of Fungi.