Science. 1981 Aug 7;213(4508):646-8. doi: 10.1126/science.213.4508.646.
Polycrystalline calcite was revealed by scanning electron microscopy of fractured skeletal ossicles of the sea star Echinaster spinulosus (Echinodermata, Asteroidea). Whisker-like calcite crystals were observed in specimens that were loaded in stress relaxation before being fractured; rapidly broken surfaces were smooth and glassy. The crystallites were 1300 angstroms wide and at least 3600 angstroms long and were packed together in lamellae. The lamellae were wound into spirals that formed the trabecular bars. All the crystallites in an ossicle appear to be aligned in the same direction. Geometric considerations indicate that the requirement for packing the crystallites smoothly may explain the high magnesium ion concentration of echinoderm calcite.
扫描电子显微镜观察海盘车（棘皮动物门，海星纲）破碎骨片发现，其由多晶方解石组成。在标本断裂前进行应力松弛加载时观察到了须状方解石晶体；快速断裂的表面光滑且呈玻璃状。微晶的宽度为 1300 埃，长度至少为 3600 埃，它们被组装成薄片。薄片缠绕成螺旋状，形成小梁条。一个骨片中的所有微晶似乎都排列在同一方向。从几何角度考虑，为了使微晶顺利组装，这可能解释了棘皮动物方解石中镁离子浓度高的原因。
