What makes it peculiar is not what is there but what is missing. A substantial heraldic shield, measuring roughly half a metre in height, was carved into the face of the stone and then left entirely blank. No coat of arms, no identifying device, no inscription anywhere on the slab. Whoever commissioned it, sometime around 1500, either never returned to complete the work or chose, for reasons now unrecoverable, to leave their monument anonymous.

The slab itself is a substantial piece of limestone, nearly two metres long and just over a metre wide, tapering slightly in thickness from base to top. It is carved in false relief, a technique where the background is cut away to leave the design standing proud of the surface, and the central feature is a seven-armed floriated cross whose fleur-de-lys terminals push right up to the raised border that frames the slab. A heavy rectangular knop, a projecting boss, sits beneath the cross-head, and the shaft meets a small stepped, curving base. Some of the upper fleur-de-lys details have been defaced, and the top corner of the slab is fractured, but the overall composition survives in reasonable condition. The scholar William Carrigan, writing in 1905, described it as a ponderous altar-tomb table and dated it to around 1500, noting the uncarved shield and absent inscription as features he found equally unremarkable and unexplained.

The friary itself, founded for the Augustinians in medieval Callan, provides the context for the slab's survival. Leaning against the east gable of the chancel, it occupies the most liturgically significant end of the ruined church, the space that would once have been closest to the high altar. The blank shield is visible on the left-hand side of the cross-shaft, its surface damaged along one vertical edge but otherwise plain and legible in its blankness. It is the kind of object that rewards a close look, less for what the carver finished than for what they did not.