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Abstract:
Sea urchin spines ofHolopneustes porossisi-musare porous single crystals, with the pores being filledwith a material rich in carbon, silicon, fluorine and so-dium. The magnesian calcite constituting the spine ishighly strained. Even though the spines appear to be sin-gle crystalline on a macroscopic scale, the calcitic materialexhibits an extended defect network. We find dislocationsas well as rotational and other, not yet identified bound-aries. We also observe within spine calcite a patterned dis-tribution of sulphur. Both distributions, that of the defectnetwork and that of sulphur resemble in their pattern toeach other and have a similar mesh size of 50 nm. Weconclude from these observations that they arise from thegrowth process of the spine and account for the mosaicitywithin the spine single crystals.
