- [l] broader:: [[animals]] - [v] [Nacre from Mollusk Shells](https://doi.org/10.1039/9781849735315-00113) - the fracture toughness of nacre exceeds that of its ingredients by several orders of magnitude. - Microscopy observations reveal substantial differences in fracture behavior of two main types of nacre, namely “columnar” and “sheet” nacre. - Sheet nacre from pearl oyster is a potential robust model for future artificial nacres