| Sea Urchin (n.) Any one of numerous species of echinoderms of the order Echinoidea. Thesaurus Entries Loch Ness monster, alevin, benthon, benthos, cetacean, crustacean, dolphin, dugong, fingerling, fish, fry, game fish, grilse, harbor seal, kipper, man-eater, man-eating shark, manatee, minnow, minny, nekton, octopus, panfish, plankton, porpoise, salmon, sea dog, sea lion, sea monster, sea pig, sea serpent, sea snake, sea urchin, seal, shark, shellfish, smolt, sponge, squid, tropical fish, walrus, whale |