It has been cut down to a rectangular block and set into the masonry south of the 1820 tower, its original purpose all but erased by whoever chose to repurpose it. Only a careful look reveals an incised circle on its surface, which may once have formed part of a cross-head, suggesting that what appears to be a plain building stone was, several centuries ago, a graveslab marking someone's burial.

The fragment dates from the 13th or 14th century and is made from fossiliferous limestone, a stone that, when cut and polished, reveals the compressed outlines of ancient marine creatures within it. It carries no inscription, so the person it originally commemorated, if it was indeed a memorial slab, is entirely unknown. The practice of reusing earlier carved stonework in later construction was common throughout medieval and post-medieval Ireland; building materials were scarce and valuable, and a trimmed slab was simply a useful block of good stone. In this case, the modification to a rectangular form removed whatever additional carving or text the slab may once have carried, leaving only that partial circle as a trace of its former identity.