文摘
Sea urchin teeth, which are used to scrape rocks for food, assume significant mechanical functions. Unraveling their design strategies could provide inspiration for the pursuit of high-performance artificial composites. In this work, we used scanning electron microscopy, transmission electron microscopy, and high-angle annular dark-field scanning transmission electron microscopy to probe the elaborate nanostructure in the stone part of Glyptocidaris crenularis tooth. Our results show that the mesocrystalline matrix, though diffracting as a single crystal, is composed of highly oriented nanocrystals and shares almost coincident crystal orientation with its central single-crystal fiber. Interestingly, the fiber and matrix are fitted together by numerous single-crystal nanostrips rather than being completely separated by an organic sheath. This sophisticated architecture may endow the tooth with sufficient structural stability to prevent catastrophic fractures.