The font itself is the more obvious object of interest, but what supports it is arguably stranger: a fragment of a limestone graveslab, reduced to a near-square pedestal measuring roughly 88 centimetres on each side and just 21 centimetres high. Only the upper right-hand portion of the original slab survives in this form, the rest having been removed with a machine saw to produce the tidy shape now visible. Cut into its surface is an incised cross and the opening words of a Latin funerary formula, "hic jacet", meaning "here lies", rendered in black letter script, the angular Gothic lettering used widely in medieval stone carving and manuscripts across western Europe.

The slab's double displacement makes it unusually difficult to read as an object. The cathedral in Cashel stands on the site of a medieval church, and the font the graveslab now supports did not originate here either; it was brought from St. John's in Kilkenny. So what visitors see is a memorial stone, origin unknown, carrying an inscription that once marked someone's burial place, now serving as the base for a font associated with an entirely different building in a different county. The "hic jacet" formula was one of the most common conventions of medieval funerary epigraphy, typically followed by the name of the deceased and a request for prayers. Here, whatever came after those two words has either been lost to damage or lies in the trimmed-away portion of the slab. The person commemorated remains completely anonymous.

The graveslab sits at the north-east end of the nave, immediately south of the chancel arch. It is easy to walk past without registering what the font is resting on, but crouching to look at the pedestal's surface reveals the incised cross and the remaining letters clearly enough. The machine-cut edges, conspicuously clean against the worn medieval stonework, mark out exactly where the original slab was shortened to fit its new role.