Top left: Scanning electron micrograph (SEM) of calcite crystals (also called prisms) isolated from the prismatic layer of Atrina rigida (pen-shell mollusk).
Top right: 3-D reconstruction of the internal structure of the calcite prisms. The blue areas represent organic-filled voids within the crystal. The technique used to acquire this image is annular dark field scanning transmission electron microscopy (ADF-STEM) tomography.
Bottom left: SEM of synthetic calcite crystals grown in an agarose hydrogel.
Bottom right: ADF-STEM tomography showing a 3-D reconstruction of the internal structure of the synethic calcite crystals grown in an agarose hydrogel. The structures outlined in blue represent the agarose fibers that are incorporated into the single crystal of calcite.
Credit: Estroff Lab, Cornell University