Correlation between Color and Elasticity in Anomia ephippium Shells: Biological Design to Enhance the Mechanical Properties.

Anomia ephippium (Oyster) shell has an inorganic "pseudo nacre" microstructure that is colored (white, yellow, orange, and red) with varying concentrations of organic polyene pigments. Using Brillouin laser light scattering, we measured the elastic constants of A. ephippium and Abalone prismatic and nacre microstructures. We find a direct correlation between the polyene concentration and the measured elastic stiffnesses of A. ephippium shells, suggesting that polyene pigment enhances the shell's primary function of mechanical protection. Further, Young's, bulk, and shear moduli of A. ephippium shells are found to surpass that of ultrastrong Abalone nacre. By studying both microstructures, we demonstrate that pseudo nacre is stiffer than nacre. This work sheds light on the structure-property relation of pseudo nacre and organic constituents that may potentially be a paradigm shift for the future mimicry of super strong biomaterials.