What are those five "Doves" you fing when you crack open a sand dollar down its middle? ?

Sand dollars have a mouth in the center of the bottom surface, and inside are these five ossicles, which are used to grind food. There are five of them because of the five-fold symmetry of the sand-dollar. The whole arrangement is known as "Aristotle's lantern" after the Greek philosopher and natural historian Aristotle, who described it.