Salenioida

The Salenioida are an order of sea urchins.

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

Taxonomy
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 †