Incident light microscopy of differently oriented shell cross-sections. Incident light microscopy. Top, orientation A; bottom, orientation B. Hierarchical structures of nacreous and prismatic shell parts are visualized best in orientation A and B, respectively. Inserts in the images on the left side are shown at higher magnification on the right. Note that in addition to the nacre lamellae there is another level of hierarchy in the range of ~20 μm, defined here as the super-structure, which is observed in orientation A at higher magnification. P, prismatic layer; N, nacre.
Schneider et al. BMC Biophysics 2012 5:19 doi:10.1186/2046-1682-5-19