The slab carries an inscription that has never been read. Two lines of text run along each side, and despite scholarly attention over more than a century, the letters or characters remain undecipherable. Whatever name or commemoration was carved into the stone, it has not given itself up.

The slab was described in 1913 by H. S. Crawford, who catalogued early cross-slabs and pillars across Ireland, as measuring roughly 1.67 metres in length and tapering from about 0.52 metres to 0.37 metres in width. At its centre is a four-line cross, a type in which four incised lines rather than a solid form define the cross shape, with what Crawford called an expanded centre, foliated extremities, meaning the arms end in leaf-like decorative flourishes, and a stepped base. This last feature, a cross rising from a tiered or staired platform, is a detail seen on early medieval Irish stonework and carries echoes of both liturgical and funerary tradition. The slab did not originate inside the cathedral. It was moved there from a site roughly 250 metres to the south-southwest, where it had been associated with a nunnery. The existence of that nunnery near Clonfert was noted during the Ordnance Survey of 1839, the findings of which were later compiled in typescript form by the Reverend M. O'Flanagan. The move into the cathedral preserved the stone, though it also separated it permanently from whatever community had once placed it over a grave.