What is the feeding structure of sea urchins called?

The feeding structure of a sea urchin is called Aristotle’s lantern.

This complex jaw apparatus surrounds the mouth and usually contains five pyramids, associated muscles, and five hard teeth. It lets many sea urchins scrape algae from rocks, grip food, and sometimes tear or grind material. The teeth are continuously renewed as they wear down.

The name comes from the traditional interpretation of Aristotle’s description of sea-urchin anatomy in his History of Animals. A historical caveat is that some modern scholars argue “lantern” may have originally referred to the overall shape of the animal rather than specifically to its jaw apparatus. Nevertheless, Aristotle’s lantern is the standard zoological term for the feeding organ.

Not every echinoid has one in the same form. Regular sea urchins typically possess the apparatus, while heart urchins and sand dollars have modified feeding systems; heart urchins notably lack a lantern. The distractor radula belongs to molluscs, while an operculum is a covering structure found in several unrelated animals.