It is a Rathdown slab, a category of medieval gravemarker particular to the coastal hinterland of Dublin and Wicklow, and this one is more unusual than most. Measuring 1.8 metres long but only 0.12 metres wide, it is an oddly narrow, misshapen piece of stone, and its carved surface is not the clean symmetrical work you might expect from a funerary monument. A crooked central band runs along its length, punctuated by four cup marks, shallow circular depressions cut into the stone. The spaces to either side of this irregular spine are filled with horizontal lines and a herringbone pattern, giving the whole surface a textile-like quality, as though someone pressed woven fabric into the stone before it set.

Rathdown-type slabs are named for the general area in which they cluster, and they represent a local medieval tradition of grave-marking that drew on both Christian and earlier ornamental conventions. This particular example was recorded and discussed by Ó hÉailidhe in 1973, and has since been secured to the western face of a buttress on the south wall of Rathmichael church, an early ecclesiastical site with a long history of settlement in this part of south Dublin. Fixing the stone to standing masonry was a practical decision to preserve it, though it does alter the experience of looking at it, presenting what would once have lain horizontal over a grave as a vertical surface mounted like a relief panel.

Rathmichael church and its surrounding graveyard are accessible to visitors, and the slab is visible on the south wall once you are within the site. The stone is relatively small in profile despite its length, so it rewards a close approach rather than a glance from a distance. The herringbone carving and the cup marks become clearer once your eye adjusts to the shallow relief. For those who want to examine the surface in detail without making the journey first, a three-dimensional digital model of the stone is available at skfb.ly/oH8wX, which allows the carved texture to be rotated and inspected in a way that flat photography rarely permits.