Are shark teeth, including megalodon teeth, made of bone?

This material is slow to decompose, which is part of the reason why fossil shark teeth are so plentiful. When a shark loses a tooth, it ends up on the bottom of the ocean, where it's covered with protective layers of sediment. It takes thousands of years for a shark tooth to turn into a fossil.

As fossilization takes place, water and minerals work their way into the shark's tooth. One fossil tooth may be red while another is gray, blue, green, or even orange. The color of a shark's tooth can be an indication of the type of minerals inside it.