SEM images of the deformed gastroliths revealed a sparse, columnar-like arrangement, with elongated radial cavities including larger than normal ACC spherules. This abnormal appearance can be attributed to the effects of partial silencing of GAP 65 production and secretion loci on the gastrolith epithelial membrane. GAP 65 deficiency is manifested both in the organization
of the chitinous matrix and in the manner by which ACC spherules are accumulated.