These fossil shark teeth come from several different types of ancient sharks including tiger, extinct great white (previously known as mako), sand, otodus, lamna, and an ancient shark called carcharodon megalodon.
If a shark loses a tooth while biting into something, another tooth from the second row would replace the missing tooth within four minutes. Thus many teeth were lost over the lifetime of a shark. Some fossilized shark teeth are found in phosphate mines, while others are collected by divers. A fossil shark tooth is easy to tell from a modern day shark tooth as a fossil shark tooth is made of stone; the modern tooth is not.