Morphogenesis of the echinoderm diamond-type stereom

PUBLICATION — Humański, K., Facchini, G., Croce, J., Kołbuk, D., Dubois, Ph., Gorzelak, P. 2026. Morphogenesis of the diamond-type stereom microlattice and the origin of saddle-shaped minimal surfaces in the echinoderm skeleton. Acta Biomaterialia, 212: 516-526. doi.org/10.1016/j.actbio.2026.01.016

Figure: The horned sea star (left) has a skeleton with a “diamond” microstructure. Using various labeling and imaging techniques (middle panel), a model of stereom growth was proposed (right panel).

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.