It's like weird Toothy truths
6. Teeth-growing machine - Shark
Humans only get two sets of teeth in our lives and the first is so rubbish the teeth fall out by age seven. The shark on the other hand has a tooth conveyor belt for a mouth. That's because they tend to fall out a lot. Instead of being fixed in the jaw bone, the shark's tooth is only held in place by their gums. Behind each tooth there are as many as five more growing behind it to replace it when it gets ripped out. A shark will get through thousands in its lifetime.