Morphogenesis of the echinoderm diamond-type stereom

The echinoderm skeleton has a remarkable microstructure known as stereom. It is composed of calcitic trabeculae with curvatures close to “saddle-shaped” forms, characteristic of minimal surfaces, whose classical physical model is soap films stretched across wire frames, and whose mathematical example is the catenoid. In some cases, the stereom displays an exceptionally regular, “diamond-like” lattice with high mechanical strength and uniform porosity. The study shows that this structure arises through coordinated growth of trabeculae. It was also demonstrated that actin fibers not only define sites of mineralization but also guide the connections and curvatures of the stereom.