The macrostructural aspect localization is similar. The difference of size is proportional to the size of adult specimens of the two species. The flat or slightly concave side on the stomach lumen side is shown. C–D: Broken gastroliths from Cherax quadricarinatus showing the semispherical and internal aspect of a gastrolith. C: the flat disc visible in the center corresponds to the oldest part of the gastrolith, i.e. the beginning of the calcium storage. D: The homogeneous dense and striated internal structure is well visible on this cross-section.