To materials scientists and engineers, stiffness, toughness, and strength are distinct and important mechanical properties. Strength is the ability of a material to stay together when stretched or compressed; stiffness is how well a material resists deformation; and toughness is the ability of a material to absorb energy before failure. Mother-of-pearl - the iridescent layer in the shells of some mollusks - has inspired a Rice University study that will help scientists and engineers judge the ultimate strength, stiffness, and toughness of composite materials for anything from nanoscale electronics to buildings. The Rice University researchers created universal maps that predict the properties of natural and biomimetic platelet-matrix composites (like mother-of-pearl) and synthetic stacks of materials like graphene. The formula relies on four characteristics of the individual materials under consideration for a composite: their length, a ratio based on their respective stiffness, their plasticity, and how they overlap. The team says their findings will work as well for materials built with nanoscale blocks as they would for a brick wall, or larger.