Calliostoma is a genus of small to medium-sized sea snails with gills and an operculum, marine gastropod molluscs within the family Calliostomatidae, the Calliostoma top snails (according to the taxonomy of Gastropoda by Bouchet & Rocroi (2005)). Previously this genus was placed within the family Trochidae. Calliostoma is the type genus of the family Calliostomatidae. The name of this genus is derived from the Greek words kallos (beautiful) and stoma (mouth), referring to the pearly aperture of the shell. The genus Calliostoma is known in fossil records from the Upper Cretaceous onwards.