A sheela-na-gig, one of those carved female figures found on ecclesiastical and secular buildings across Ireland and Britain, has been worked into the quoin at the north-east angle of the chancel wall. Sheela-na-gigs typically depict a naked female form in an explicit pose, their precise meaning still debated by scholars; theories range from protective talismans to moral warnings to survivals of pre-Christian belief. This particular example is carved in false relief on red sandstone and set within a frame, and it has the quality of something trying not to be noticed, which, given the lichen steadily creeping across it, may soon be the case.

The figure was recorded by Hartnett as early as 1954, and scholar Barbara Freitag later described it in some detail in her 2004 study. Freitag's description is precise and unsentimental: a big, earless head with a flat face, downcast eyes, and a drooping mouth; a short neck and squat body with no ribs or breasts, though the navel is clearly indicated. Only the left arm is discernible, held straight with the hand resting on the thigh. The legs are straight, with a long vertical vulva between them, and the feet are absent, most likely cut away when the stone was trimmed to fit its current position. That repositioning is itself significant. Freitag concluded that this is not the stone's original location; the lower part of the quoin has been cut off to accommodate it, suggesting the figure was moved at some point and inserted here as a kind of retrofit rather than placed during the church's original construction.

The church sits within Malahide Demesne in north County Dublin, and the sheela-na-gig occupies the north-east corner of the chancel, which is the eastern, altar end of the building. Visitors should look carefully at the quoin stones at that angle; the figure is not large and the growing lichen makes it harder to read with each passing season. For those who find the carving difficult to interpret in person, a 3D model created by Digital Heritage Age is accessible on the Sketchfab website at skfb.ly/6vH9r, allowing a closer examination of the form than the stone itself currently permits.