Limpets need super strong teeth because they use them to hang on to rocks along the seashore. They also use the teeth to scrape algae off the rocks for food, often picking up pieces of rock in the process. The teeth are made of iron-filled goethite nanofibers that are part of a protein matrix. The material is 100 times thinner in diameter than a human hair, and can withstand tensions of up to 3.0 to 6.5 gigapascals. Imagine a strand of spaghetti holding up 3,000 pounds and you've got the idea, lead author Asa Barber told the BBC.