Echinoidea
(Science: zoology) The class echinodermata which includes the sea urchins. They have a calcareous, usually more or less spheroidal or disk-shaped, composed of many united plates, and covered with movable spines. See spatangoid, Clypeastroid.
alternative forms: Echinidea, and Echinoida.
Origin: NL. See echinus, and -oid.
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