Castledermot in County Kildare is already well supplied with early medieval stonework, from its round tower to its pair of granite high crosses, so it takes something particular to stand apart from that company. A small limestone fragment, less than half a metre long and no more than seven centimetres thick, does exactly that, not through scale but through the quiet precision of what was cut into its surface.

The stone is a cross-slab fragment, a category of early Christian monument in which a flat face of rock is carved with a cross rather than shaped into a freestanding sculpture. On this piece, an incised narrow-shafted cross rises from a stepped base, with three discs punctuating the shaft itself. The steps at the base are a motif with roots in representations of Calvary, the hill on which the crucifixion took place, and their presence here links a modest local fragment to a wider visual vocabulary shared across early medieval Ireland and beyond. The three discs on the shaft are less commonly seen and add a degree of individuality to what might otherwise read as a conventional design. The dimensions recorded by Bradley and colleagues in 1986 place it at 0.49 metres in length and between 0.29 and 0.34 metres in width, the slight variation in width suggesting the stone was already broken or irregular when measured.