They are distinguished from other sea urchins by the presence of a large plate on the upper surface, with the anus to one side. They have very large tubercles between the ambulacral plates, and much smaller ones on the ambulacral plates themselves.

According to World Register of Marine Species :

• family Saleniidae L. Agassiz, 1838
• family Acrosaleniidae Gregory, 1900†
• family Goniophoridae Smith & Wright, 1990†
• family Hyposaleniidae Mortensen, 1934†
• family Pseudosaleniidae Vadet, 1999b†

• Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 980. ISBN 0-03-056747-5.
• National History Museum. "Selenioida". Retrieved 19 Dec 2009.