Echinothurioida

Echinothurioida

[‚ek·ə·nō·thu̇·rē′ȯid·ə] (invertebrate zoology) An order of echinoderms in the superorder Diadematacea with solid or hollow primary radioles, diademoid ambulacral plates, noncrenulate tubercles, and the anus within the apical system.