Miocene. Carcharodon megalodon. WHITE 133mm/5.3in. This prehistoric shark wasn't a man-eater, it was a whale eater! An adult megalodon could reach sizes of up to 70ft long, for comparison the closely related Great White Sharks of today reach sizes of barely over 20ft and the largest Killer Whale was 32ft long. This tooth is a big 5" long.