It is a sheela-na-gig, one of the medieval stone carvings found on churches and castles across Ireland and Britain, depicting a female figure in an explicitly sexual pose. The Dunnaman example sits slightly off-centre to the south of the wall face, embedded in the masonry as though it has always been there, which for all practical purposes it has.

The carving was first formally noted in 1865 by the Earl of Dunraven, who described it with a mixture of scholarly precision and Victorian discomfort, calling it representative of a class of stones "so strange in their character" and depicting the female figure "in the most repulsive way." His account appeared alongside a woodcut of the eastern elevation of the tower, marking the figure's position relative to the windows nearby. The carving was recorded again in 2001 by McMahon and Roberts, and described in detail by the scholar Barbara Freitag in 2004. Her account is clinical and thorough: a large figure set within a frame, with a roundish head bearing billowy lines across the forehead, oval eyes, a wedge nose, and an open mouth. The arms are extremely long, the armpits open, and the hands pass beneath the thighs to grasp the vulva, which is oval-shaped and hangs between widely splayed legs. The ribcage is heavily incised and extends down over the abdomen. The large toes touch the edge of the frame, and directly beneath the vulva sits an egg-shaped object whose significance remains, as with much about these carvings, a matter of debate.

Dunnaman Castle itself is a tower house, the type of fortified residential structure built across Ireland from roughly the fourteenth to the seventeenth centuries, and the sheela is fixed to its external eastern face at the halfway point of the wall. Visitors approaching from the east will have the best view of the carving, though reaching it requires navigating what is, in this part of Limerick, typical rural farmland. The figure is not at eye level, sitting as it does at second-floor height, so a position a little distance back from the base of the wall gives the clearest sightline. The egg-shaped object beneath the figure is easy to miss but worth looking for once the rest of the carving has resolved itself against the stone.