The Brittle Star Ophiocoma Wendtii
Scanning electron micrograph (SEM) of a part of the skeleton of a brittlestar Ophiocoma wendtii (Ophioroidea, Echinodermata). The entire structure (the mesh and the array of microlenses) is composed of a single calcite crystal used by the organism for mechanical and optical functions.
Joanna Aizenberg, David A. Muller, John L. Grazul, D. R. Hamann. Science 299, 1205 (2003).
Image courtesy: Dr. Joanna Aizenberg, Harvard.