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(phylum Echinodermata)

A subphylum of echinoderms that have radial symmetry, a tendency to produce a cup-shaped or globoid, plated test (theca), and appendages (brachioles or arms) which support exothecal extensions of feeding ambulacra. The subphylum includes eight classes, seven of which were extinct by the end of the Palaeozoic, with only the Crinoidea surviving to the present day.

Subjects: Zoology and Animal Sciences.

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