Short, plug-shaped, vertical burrow, with an elliptical base and a central depression at the basal end. Burrow borders are smooth, with very discrete lining. Ornaments are absent. Burrow fill is similar to that of the host rock. Minimum diameter of the basal end is 17.3 mm, maximum is 19.25 mm; maximum height preserved is 4.75 mm. Preservation in positive hyporelief.