These fossil shark teeth come from a shark called a Great White, the only living White Shark. 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.
The fossil shark teeth are often found in phosphate mines, and sometimes in beach areas. Some teeth are found by divers. A fossil shark tooth is easy to tell from a modern day shark tooth as a fossil tooth is made of stone and the modern tooth is not.