Sea urchins employ as wide a range of composite reinforcement strategies as are seen in engineering composites. Besides tailoring reinforcement morphology and alignment to the functional demands of position, solid solution strengthening (high Mg calcite), inclusion toughening (macromolecules), functional gradients in mineral reinforcement morphology, composition and dimensions and mineral interface tailoring are other tactics important to achieving high toughness and high strength in sea urchin teeth. Teeth from different echinoid families illustrate combinations of reinforcement parameters and toughening mechanisms providing good functionality, a virtual probe of the available design space. This paper focuses on a multi-mode x-ray investigation of sea urchin teeth studied on scales approaching 1 µm in millimeter-sized samples, in particular mapping 3-D microarchitecture with synchrotron and laboratory microCT and mapping Ca1-xMgxCO3 crystal composition x and microstrain and crystallite size via microbeam diffraction.
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