Abstract: In this paper, the effect of stereom structure on the mechanical behavior of the Sea Urchin Inorganic Skeleton (SUIS) has been studied. The stereom microstructure of both Anthocidaris crassispina and Tripnenstes gratilla was characterized by Scanning Electron Microscopy (SEM). Results indicate that a three-layer porous structure consisting of a growth, a support, and a resorption (GSR) layer is a common denominator for both species. The effect of GSR layer order on the mechanical behavior of the SUIS was studied by a finite element method. The results show that the GSR model could effectively reduce the maximum tensile stress on its meridional sutures under unidirectional pressure, hydrostatic pressure, and self-weight situation. For a fabricated three-layered ceramic test strips with different layer orders, the mechanical properties have a completely opposite performance compared with the compressive properties of the calculated SUIS-like models. This indicates that the GSR structure can effectively improve the mechanical properties of the SUIS, but it cannot be applied to bionics without considering its synergistic effect with the macro-structure of the SUIS. This is a typical example of bionic invalidation by single structure, where multi-level structure bionics may be an effective solution.

Key words: porous multilayered structure, finite element analysis, stress transfer, mechanical properties, sea urchin test