Ophiocistioidea

Ophiocistioidea

[‚äf·ē·ō‚sis·tē′ȯid·ē·ə]
(paleontology)
A small class of extinct Echinozoa in which the domed aboral surface of the test was roofed by polygonal plates and carried an anal pyramid.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.