The article explores the mechanical properties of natural nanocomposites such as bone, tooth, and nacre, highlighting the importance of the nanometer scale in achieving superior strength and robustness. The authors argue that the nanometer size of mineral particles in these materials is crucial for optimizing fracture strength and maximizing tolerance to flaws. They present a generic mechanical model that explains how the large aspect ratio of mineral platelets compensates for the low modulus of the protein matrix, leading to high stiffness. The study also challenges the widely accepted engineering concept of stress concentration at flaws, showing that materials become insensitive to flaws once the structural size reaches a critical length. This finding has significant implications for the design of new nanomaterials and the understanding of hierarchical structures in biological materials.The article explores the mechanical properties of natural nanocomposites such as bone, tooth, and nacre, highlighting the importance of the nanometer scale in achieving superior strength and robustness. The authors argue that the nanometer size of mineral particles in these materials is crucial for optimizing fracture strength and maximizing tolerance to flaws. They present a generic mechanical model that explains how the large aspect ratio of mineral platelets compensates for the low modulus of the protein matrix, leading to high stiffness. The study also challenges the widely accepted engineering concept of stress concentration at flaws, showing that materials become insensitive to flaws once the structural size reaches a critical length. This finding has significant implications for the design of new nanomaterials and the understanding of hierarchical structures in biological materials.