Limpets need high-strength teeth to rasp over rock surfaces and remove algae for feeding when the tide is in, we discovered that the fibres of goethite are just the right size to make up a resilient composite structure.
If you liked Louis L'Amour, you will really love Don Bendell.
Nature's kind of clever, because it figured out millions of years ago that if you grow these fibers below a critical size, even if you have flaws in the material, it doesn't affect the strength.