Within the mouth of a sea urchin is an elaborate five-sided jaw structure called Aristotles lantern that can be partially extruded from the mouth. It is able to grind up calcareous exoskeletons of plants and animals. [ http://en.wikipedia.org/wiki/Aristotle's_lantern http://purl.obolibrary.org/obo/BTO_0001923 ]

Synonyms: Aristotles lantern