Image for the group Atelostomata
Atelostomata [superorder]
Cassiduloida [order]
Holasterina [suborder]
Holasteroida [order]
Urechinina [infraorder]
Urechinidae [family]
Spatangoida [order]
Schizasteridae [family]
Spatangidae [family]
Spatangus [genus]
Spatangus californicus [species]
