Holasteroida are distinguished from their sister group the Spatangoida by their apical disc structure and by their plastron architecture. Spatangoids have an amphisternous or protoamphisternous plastron in which the first pair of plates following the labral plate are distinctly enlarged, and their apical disc never has oculars II and IV meeting behind the anterior genital plates.
The following taxon is too poorly known to be placed with confidence within any holasteroid grouping:
Corechinus Kongiel, 1936; Upper Cretaceous, Poland.
Titanaster Szorenyi, in Mortensen, 1950; Eocene, Hungary