Abstract: Seashells, commonly referred to as nature’s armors against predatory attacks, have been serving as the inspirations for designing strong and tough engineering materials. Previous studies on conch shells have been focused on the shell body parts. The conch spines which are evenly distributed at the tail of conch shell are generally accepted as the decoration, enabling conch shells as art pieces. Here we report a new finding that nature uses curved reinforcements, different from the straight ones in conch body parts, to construct conch spines which exhibit 30% increase in fracture strength compared to conch shell body parts. The curved lamellae not only endow conch spines with pyramid-shape but also add extra shielding to the shells. Under equilibrium state, the curved lamellar configuration withholds 3 times higher loading than the straight one. Our finding uncovered nature’s wisdom in constructing seashells and provides an additional design guideline for utilizing curved reinforcements to achieve multifunctionalities and superior mechanical prowess.

Key words: conch shell spine, composite, curved reinforcement, hierarchical structure, fracture strength