Diagnosis: Solitary to rarely paired Nihilichnus with mainly ellipsoidal to sometimes circular outline. The hole margin is straight and perpendicular to the inner and outer surfaces. Very few small scratches may be present on the shell surface in close vicinity to the holes.

Emended diagnosis: Solitary to rarely paired holes or external pits, with mainly elliptical to sometimes circular outline, in invertebrate shell. The hole margin is straight and perpendicular to the inner and outer surfaces. Very few small scratches may be present on the shell surface in close vicinity to the holes.