It is not the most conspicuous object in the world, but look closely and the carved lines resolve into something deliberate and considered: a wheeled cross, the kind of ringed form that appears across early medieval Ireland, incised here with double lines, its centre squared off and its arms ending in expanded rectangular terminals. The oratory itself is a small early Christian stone church, and the slab fits the company it keeps.

The two fragments were found in 1934 at St Flannan's well, a holy well associated with the same local cult that gives the oratory its name. Holy wells in Ireland were frequently sites of long-term veneration, and objects recovered near them often carry the accumulated weight of centuries of use. This slab, cut from yellow sandstone, would originally have stood as a single upright marker. The upper piece preserves the cross head; the lower preserves the tapering shaft and, at its base, a tenon, the projecting tongue of stone that would have slotted into a socket to keep the whole slab upright in the ground. The two fragments together measure roughly a metre and a quarter in combined height. Bradley and colleagues recorded the piece in 1988, by which point it had already been secured indoors, spared the slow attrition that open-air exposure would have continued to cause.