Cassiduloida

Cassiduloida is an order of sea urchins. The group was extremely diverse with many families and species during the Mesozoic, but today, only seven extant species remain.

Apatopygidae is a family of echinoderms belonging to the order Cassiduloida.

Echinolampadidae is a family of cassiduloid echinoids.

Neolampadidae is a family of echinoderms belonging to the order Cassiduloida.

Cassidulidae is a family of echinoderms belonging to the order Cassiduloida.

Hardouinia is an extinct genus of echinoids that lived in the Late Cretaceous. Its remains have been found in North America.

Echinolampas is a genus of echinoderms belonging to the family Echinolampadidae.