A mural monument, sometimes called a wall monument, is a commemorative tablet fixed directly to a church wall rather than laid flat as a floor slab. This one was carved in fossiliferous limestone, the kind of stone in which the outlines of ancient marine creatures are still faintly legible, and it was made in 1636 to honour a merchant who, unusually, commissioned it for himself while still alive.

The monument commemorates Jacob Archdeacon, described in the Latin inscription as a merchant and burgess of the city of Kilkenny, and his wife Catherine Woodlocke. The inscription, cut in false relief Roman capitals, states plainly that Jacob erected the monument during his own lifetime, for himself, his wife, and their descendants. Blanks were left in the text for the dates of their deaths to be filled in later, and those blanks remain unfilled, lending the stone an oddly unfinished quality. Below the biographical text runs an epitaph in Latin verse, ending with the line "Sternum ut possis vivere disce mori", meaning roughly "Learn to die, so that you may live for ever", dated 1636. The upper section, a triangular armorial plaque, carries a heraldic shield wreathed in carved foliage, with the initials IA and KW flanking it and the motto DEVS PROVIDEBIT, "God will take care of us", inscribed beneath. The two sections, originally a single composed monument, were placed on the wall of the so-called Monuments Room in the church's north transept around 1960, then removed from that wall in 2015 and repositioned against the east wall of the same transept, where they now rest in their present, slightly disjointed arrangement.