Spider silk is famous for its amazing toughness, and until recently a tensile strength of 1.3 gigapascals (GPa) was enough to earn it the title of strongest natural material. However, researchers report online today in the Journal of the Royal Society Interface that the record books need to be updated to properly recognize the incredible strength of the limpet teeth. Marine snails known as limpets (Patella vulgata, pictured) spend most of their lives scraping a set of small teeth along rocks in shallow ocean waters, looking for food. The constant grinding would be enough to quickly reduce most natural materials to nubs, but the limpets’ teeth boast a tensile strength of between 3 and 6.5 GPa, researchers report. Scientists discovered that the teeth are made of a mixture of goethite (an iron-containing crystal) nanofibers encased in a protein matrix. In spite of their amazing strength, the teeth don’t quite best the strongest humanmade materials like graphene, but the new material’s upper range puts it far ahead of Kevlar and on par with the highest quality carbon fibers. Researchers speculate that the material’s durability may have practical applications in dentistry, but it’ll probably be a while before anyone is trading in their own teeth for some limpet chompers.