At St Mary's parish church in Kilkenny, the removal of a blocking wall that had sealed off the southern nave arcade since 1740 revealed something that had been quietly entombed within the masonry: a fragment of a 16th-century grave slab, hidden for the better part of three centuries.

The piece is a section of what would once have been the mensa or ledger of a chest tomb, a type of raised box tomb common in late medieval Ireland in which a flat stone lid, the mensa, sits atop a decorated chest-like base. This particular fragment is composed of fossiliferous limestone, a stone that preserves the outlines of ancient shells and marine organisms within its surface, and would originally have formed part of a substantial monument. It was discovered during work documented by Cóilín Ó Drisceoil in 2019. How the slab came to be used as building material when the arcade was blocked in 1740 is not recorded, though the reuse of earlier stonework in later construction was far from unusual in post-medieval Irish churches. The fragment is currently stored in the north-east corner of the southern side of the graveyard at St Mary's.