(subphylum Echinozoa, class Echinoidea)
A superorder of irregular echinoids characterized by the lack of compound ambulacra, Aristotle's lantern, girdle, or gill slits. The apical system and peristome are rarely opposite, and the interambulacra are wider than the ambulacra on the lower surface. The superorder includes the orders Disasteroida, Holasteroida, and Spatangoida.
Subjects: Zoology and Animal Sciences.