An order of Diadematacea, making up those genera that possess solid spines and a rigid test. The ambulacra show typical diadematoid structure, and the tubercles are noncrenulate. The single known family, Pedinidae, includes 15 genera, ranging from the Late Triassic onward, although only one genus, Caenopedina, survives today; the latter inhabits the Indo-Pacific and Caribbean seas, ranging from the continental shelf down to 660 ft (2000 m).