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Temporal range: Lower Permian–Recent
Cidaris cidaris MHNT.jpg
Cidaris cidaris
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Subclass: Perischoechinoidea
Order: Cidaroida
Claus, 1880


Cidaroida is an order of primitive sea urchins, the only living order of the subclass Perischoechinoidea. All other orders of this subclass, which were even more primitive than the living forms, became extinct during the Mesozoic.


Their primary spines are much more widely separated than in other sea urchins, and they have no gills. Other primitive features include relatively simple plates in the test, and the ambulacral plates continuing as a series across the membrane that surrounds the mouth.

List of families[edit]

Many different fossil Cidaroid radiola (MNHN).

According to World Register of Marine Species:[1]

See also[edit]


  1. ^ Kroh, A. (2013). "Cidaroida". World Register of Marine Species. Retrieved 2013-12-31.