Topological interlocking and geometric stiffening as complementary strategies for strong plant shells

摘要: Many organisms encapsulate their embryos in hard, protective shells. While birds and reptiles largely rely on mineralized shells, plants often develop highly robust lignocellulosic Despite the abundance of hard plant particularly nutshells, it remains unclear which fundamental properties drive mechanical stability. This multiscale analysis six prominent (nut)shells (pine, pistachio, walnut, pecan, hazelnut, macadamia) reveals geometric structural strengthening mechanisms cellular macroscopic length scales. The strongest tissues, found walnut exploit topological interlocking 3D-puzzle cells thereby outperform fiber-reinforced structure macadamia under tensile compressive loading. On scale, occurs via an increased shell thickness, spherical shape, small size, a lack extended sutures. These functional interrelations suggest that simple modifications are powerful resource-efficient strategy for to enhance fracture resistance entire shells tissues. Understanding interplay between structure, geometry, mechanics provides new perspectives evolutionary diversification seed coats, as well insights nutshell-based material applications.