(Sarah of the Clue Crew delivers the clue) Sea urchins' body symmetry makes their teeth fit together in a way that this pupil of Plato compared to a five-sided lantern.  2300 years later, it's still known as his lantern
[DOC] [TLE] Sea urchin - Wikipedia [PAR] Sea urchins or urchins archaically called sea hedgehogs, are small, spiny, 
globular animals ... Like other echinoderms, they have five-fold symmetry (called 
pentamerism) ...