Figure 1. Epofix cast of a late Pleistocene fragment of Arctica islandica (Bivalvia), locality 9801, Pyoza river (northern Russia). The embedded fragment, which has an aragonitic homogenous shell structure, became radially sectioned and partially etched with hydrochloric acid (4.0 percent by volume). The cast of an elongated boring appeared. The external shell surface is toward right. Scanning electron micrograph, scale 0.1 mm.