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Arbacioida

Arbacioida
Temporal range: Middle Jurassic–recent
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Superorder: Echinacea
Order: Arbacioida
Gregory, 1900
Family: Arbaciidae
Gray, 1855

The Arbacioida are an order of sea urchins, consisting of a single family, the Arbaciidae. They are distinguished from other sea urchins by the presence of five separate plates around the anus. Unlike their close relatives, the Salenioida, all of the tubercles on their tests are of similar size. It contains these genera:




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Wikipedia

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