Astreus hygrometricus is a type of fungus that belongs to the family of Diplocystaceae. It is commonly known as the hygroscopic earthstar and is widely distributed across different continents. There are several synonyms that are commonly used to refer to this species of fungus. These include Myriostoma coliforme, Geaster coliformis, Geaster hygrometricus, and Earthstar fungus. The hygroscopic nature of this fungus refers to its ability to absorb and release moisture from the surrounding environment for regulating its spore discharge. Astreus hygrometricus is a fascinating specimen that is popular among fungi enthusiasts and researchers alike.