Atelostomata

The Atelostomata are a type of sea urchins. They are distinguished from other sea urchins by their irregular shape and the absence of a feeding lantern. The group includes the well known heart urchins, as well as some less familiar and extinct forms.

List of orders

 * Family † Acrolusiidae Mintz, 1968
 * Family † Collyritidae d'Orbigny, 1853
 * Family † Disasteridae Gras, 1848
 * order Holasteroida (Durham & Melville, 1957)
 * order Spatangoida (L. Agassiz, 1840)
 * Family † Tithoniidae Mintz, 1968