smellzlikefish
Contributor
Those are parts of an apparatus in echinoderms (urchins and sand dollars) known as "Aristotle's Lantern." It can be found on the underside of the creatures.
As for the shark tooth/size estimation, because all sharks have different dentition and the size of the teeth varies from small at the corners of the mouth to large at the center (And many of these teeth are pretty similar in appearance), it is impossible to judge with any accuracy the size of the shark based on its tooth size.
As for the shark tooth/size estimation, because all sharks have different dentition and the size of the teeth varies from small at the corners of the mouth to large at the center (And many of these teeth are pretty similar in appearance), it is impossible to judge with any accuracy the size of the shark based on its tooth size.
