Mechanical design of the highly porous cuttlebone: A bioceramic hard buoyancy tank for cuttlefish

Significance Cellular solids, or foams, are an important class of structural materials for packaging, transportation, and infrastructure due to their mechanical efficiency. Current foams are primarily made of metallic or polymeric materials, while ceramics could potentially serve this goal better, as they have higher specific stiffness and strength, and are chemically more stable. What limits the application of ceramic cellular solids as structural components are their brittleness and flaw sensitivity. Overcoming the fragile nature of ceramic foams, making them lighter while reaching higher stiffness, strength, and energy absorption is challenging but critical toward many applications. In this study, we elucidate how cuttlebone overcomes its intrinsic brittleness through the “wall–septa” microstructure, which could inspire the development of lightweight ceramic cellular solids.