Shark
Sharks have different-shaped teeth, depending on what they eat. For instance, some sharks have sharp, pointy teeth, while bottom dwelling sharks have cone-shaped teeth for crushing shells. Because there are so many different kinds of sharks, and because each kind has its own kind of special teeth, many people enjoy collecting shark teeth. Shark teeth collectors can guess how large a shark was by measuring the shark tooth. First, they measure the length of the tooth in inches. Every inch of tooth equals 10ft of shark length: so if a shark tooth is 2 inches long, the tooth came from a shark that was 20 ft long! Even more terrifying is that some of the Megalodon teeth are 6 inches long so that suggests a shark 60 feet long.