In the graveyard at Castledermot, a flat slab of granite lies on the ground with a Latin cross carved into its surface, slightly off-centre, as though whoever placed the design had second thoughts midway through the work. That small displacement, easy to miss if you are not looking closely, gives the stone an oddly human quality amid an otherwise carefully composed ecclesiastical landscape.

The slab is recumbent and tapers gently along its length, measuring 1.7 metres long and between 0.28 and 0.41 metres wide, with a thickness of around 0.18 metres. The cross is carved in relief rather than incised, meaning it rises from the surface rather than being cut into it, and at its centre sits a circular boss roughly 15 centimetres in diameter. This kind of carved cross-slab is a relatively common survival from early medieval Ireland, serving variously as grave markers or commemorative stones associated with monastic sites. Castledermot itself was an important early Christian foundation in County Kildare, and the graveyard still holds several significant carved stones. This particular slab lies to the west of the South Cross, one of the site's well-known high crosses, placing it within a cluster of early medieval stonework that has endured in various states of preservation.