The type species differs from all non-urechinid holasterids in having the posterior ocular plates only in tenuous connection with the posterior paired genital plates. The left posterior ocular plate touches the right posterior genital plate but not the left posterior genital plate and the right posterior ocular plate is distal to the left posterior ocular plate and removed from its genital plate (see figure above). Proholaster Gauthier, 1896, from the early Cretaceous of Tunisia is very similar, but has the posterior oculars completely separated from the posterior genital plates and has a distinct anterior sulcus.
Solovjev, A. 1989. New echinoid genus Eoholaster (Spatangoida, Holasteridae) from the Berriasian. In: Fossil and recent echinoderm researches. Academy of Sciences of the Estonian SSR, Institute of Geology and Academy of Sciences of the USSR. Tallinn. Pp. 148-155.