Slight misorientations in nacre start as spherulites. Aragonite nacre from the California red abalone H. rufescens. Nacre growth proceeds in the bottom-to-top direction in this cross-section. It is interrupted, an organic dark horizontal layer is formed, then spherulites nucleate, then nacre growth restarts. Notice that the c-axis orientations 10° from the normal to nacre layers (including bluish-cyan, cyan, and greenish-cyan) rapidly prevail as other orientations disappear, such as green, blue, magenta, and yellow in the spherulitic layer and just above it in the first few tens of nacre layers formed epitaxially on spherulites.
