Vestigichnus discus Radtke, Hook, Campbell et Golubic, 2024

Key feature (diagnosis): V. discus or “plaque morph” (Fig. 18d, centre) consists of shallow circular lens-like depressions, up to 100 μm in diameter but only a few micrometres deep. Two superimposed well-expressed and preserved circular plaque traces with sharp etch marks expressed are illustrated in an SEM image that includes views of the resin-cast surface replicas of a pteropod shell (e.g. 18d, centre), and finer detail (Fig. 18e). The detail shows that the etch patterns conform to the mineral organization of the shell with exposed outlines of the crystal boundaries of the shell substrate.