Aristotle's Lantern

The Aristotle's lantern is considered the mouth of the sea urchin. It's used for biting and rasping.

The teeth is the only element of the lantern that protrudes of the mouth.

The lantern is composed by 5 teeth.

Thanks to the different set of muscles present, the lantern can be extended and retracted. The resulting pressure difference within the test is equalized by the madreporite on the aboral side of the test.