Rather than lying flat over a grave, it was set on its side and used as a lintel, spanning the north doorway of a postern tower at first-floor level. A postern was a secondary or service entrance, the kind of opening used for daily movement rather than ceremony, which makes the repurposing all the more matter-of-fact. Whoever reused this piece of dressed stone was solving a practical problem, and the slab's funerary origins appear to have been of little concern.

The slab itself is modest in size, tapering from around 36 centimetres wide at the top to 29 centimetres at the base, just under a metre in length. It has split in two directions, horizontally across its width and again down its length, though enough survives to make out the incised decoration: a cross with its shaft still clearly visible, and part of a trefoil, the three-lobed motif common in medieval ecclesiastical carving. One edge is chamfered, the other carries a slight round bevel. On stylistic grounds it has been dated to the late thirteenth century. Kells Priory, founded for Augustinian canons, the order of priests who followed the Rule of Saint Augustine and combined monastic life with pastoral work, contains a remarkable concentration of such slabs. Dozens have been recorded across the site, catalogued and described by the researcher J. Higgins, whose 2007 study of the priory's medieval funerary monuments placed this particular stone as catalogue number four in the sequence.