KnowraSea urchinLinked fromLinked fromThe 15 pages that link to Sea urchin, each with the reason it gives.All 15Broader topic 2Related 8Narrower topic 1Compared with 4Sea cucumberCompared with: Its hard test contrasts with the flexible, elongated sea cucumber body.Brittle starCompared with: Its compact, spine-covered body contrasts with the brittle star's distinct disc and flexible arms.StarfishCompared with: Sea urchins share the echinoderm body plan but lack the starfish’s prominent arms.ParrotfishCompared with: Sea urchins also control reef algae, but graze with teeth arranged in Aristotle’s lantern.