Echinoderm n. : One of the Echinodermata.

Example:


Taxonomy
echinoderms, sea urchins, starfish, sea cucumbers, organisms, crinoids, skeleton, brittle stars, tube feet, spines, arms, chordates, plates, radial symmetry, phylum Echinodermata, sessile, body, surfaces.

Defination from the web:
Echinoderms are traditionally recognised: the more familiar, motile Eleutherozoa, which encompasses the Asteroidea ... The development of an echinoderm begins with a bilaterally symmetrical embryo, with a coeloblastula developing first. ...