| Cassiduloida Temporal range: Lower Jurassic–recent |
|
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Superorder: | Atelostomata |
| Order: | Cassiduloida Agassiz, 1847 |
| Families | |
|
Echinolampadidae |
|
The Cassiduloida are an order of sea urchins. The group contained many families and species during the Mesozoic, but today, only a few species survive.
Cassiduloids have a rounded or slightly oval appearance, and look somewhat similar to sand dollars, although they are actually more closely related to the heart urchins. They are distinguished from other sea urchins by the presence of smaller intervening areas between the main ambulacral areas on the oral surface. They have no lantern, and the petaloids are poorly developed or absent.