Differs from Sternotaxis in having biserial plastron plating rather than uniserial plating, and in lacking a marginal fasciole. Cibaster and Offaster differ primarily by possessing a marginal fasciole and a better developed anterior sulcus. Crassiholaster has a much thicker test, smaller, more anterior peristome opening into a shallow frontal groove, and more rounded lower surface but is otherwise identical in plate architecture.
Smith, A. B. & Wright, C. W. 2003. British Cretaceous echinoids. Part 7, Atelostomata, 1. Holasteroida. Palaeontographical Society Monographs, London. Pp. 440-568, pls 139-182.
Smith, A. B., Paul, C. R. C., Gale, A. S. & Donovan, S. K. 1988. Cenomanian and Lower Turonian echinoderms from Wilmington, south-east Devon, England. Bulletin of the British Museum (Natural History) Geology series 42, 1-244.