Figure 3: Quasi-planar nanoscale view at the onset of mollusc nacre growth shown by HAADF-STEM.

Nacre growth begins by aggregation of nanocrystals in the organic matrix that separates the prismatic from the nacreous growth (lower left). As growth progresses (towards top right), the nanocrystals aggregate and grow with disordered, often needle-like, geometries. When a critical packing density is reached, continuous early-nacre platelets form—later leading to the familiar large, uniform nacre plates. The quasi-planar section geometry is illustrated in bottom inset.