The worn text runs along the right-hand edge of the stone, and scholars remain unsure whether it is Old Irish lettering or Norman-French in Lombardic script, the rounded, decorative letterforms common in medieval manuscript and stone carving. That ambiguity is itself a small puzzle; it places the person commemorated here at an oblique angle to the cultural and linguistic crossroads of medieval Ireland, where Gaelic and Anglo-Norman worlds overlapped and sometimes blurred together.

The slab is a substantial piece of work, nearly two metres long and tapering from sixty centimetres wide at the head to thirty-five at the foot, cut from limestone and finished with chamfered, diagonally tooled sides. Its surface is framed by a raised border, and the decoration is carved in raised relief rather than incised, giving it a legible presence even after centuries of wear. The central motif is a four-armed cross with fleur-de-lys terminals, the stylised lily-like ornament that appears frequently on high-status medieval stonework, and the shaft of the cross terminates in a further fleur-de-lys at the base. Just below the cross-head sits a knop, a small rounded projection, and from either side of the shaft beneath it spring two foliate sprigs, giving the composition a controlled, organic quality. Stylistically, the slab belongs to the thirteenth or fourteenth century, a period when such decorative programmes were well established across Ireland and Britain. It is not alone in the church; another graveslab lies immediately to its west, and two further fragments from the same general period survive elsewhere within the building, suggesting that Tullaherin was a site of some local significance for commemorative burial.