What is the strongest material in the wild world?

Researchers at the University of Portsmouth in the UK studying an aquatic snail called a limpet (circle) have found that their 1-mm-long teeth are composed of the strongest biological material in the world. An iron-containing mineral packed in protein enables these teeth to tolerate a tensile stress of 4.9 billion pascal. In comparison: A human tooth withstands pressure of 500 million pascal at most. The strength of limpet teeth (macro view, top) even surpasses that of spider silk.