Sea urchin

Class of marine invertebrates

Sea urchins or urchins are the class Echinoidea within the echinoderms. Approximately 950 species live on the seabed, inhabiting all oceans and depths from the intertidal zone to the deep sea. They typically have a globular body covered by spiny protective tests (hard shells), typically from 3 to 10 cm (1 to 4 in) across.

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