Nacre—the iridescent part of mollusk shells—is a poster child for biologically inspired design. Despite being made of brittle chalk, the intricately layered microstructure of nacre gives it a remarkable ability to resist the spread of cracks, a material property known as toughness.
Click here for original story, Not all of nature’s layered structures are tough as animal shells and antlers, study finds
Source: Phys.org