Check out this whale tooth. This, believe it or not, is the left central incisor of the male Narwhal whale. The right incisor is there, but remains small and does not protrude. It is interesting not only because is it beautiful and unusual, but because the structure is similar but different than regular teeth. Most teeth have the pulp chamber inside with a layer of odontoblasts or cells that produce the dentin. The dentin has many small tubules. The outer layer is the hard enamel. Well, the narwhal tooth does not have enamel, just a cementum covering like the root of a tooth. Some people think the tubules enable the whale to sense their environment. This whale's "tusk" looks like a unicorn doesn't it. Pretty cool huh?