It is easy to overlook: low to the ground, just over a metre in length, and oriented north to south in the quiet northeastern corner of the burial ground. What distinguishes it is a carefully cut socket near its southern end, a small rectangular void measuring roughly nineteen centimetres long and nine centimetres wide, evidently designed to hold an upright cross that no longer survives. The socket itself sits eighteen centimetres from the stone's southern tip, with the longer portion of the stone, some fifty-six centimetres, extending northward. The whole assembly is a kind of mortise without its tenon, a mount without its object.

Inis Cealtra, sometimes anglicised as Inishcaltra or Holy Island, sits in the southern reaches of Lough Derg on the Shannon. It was an important monastic site from at least the early medieval period, associated with Saint Caimin and drawing pilgrims and patrons across many centuries. The Saint's graveyard is one of several distinct ecclesiastical zones on the island, a place where the dead were interred close to the spiritual prestige of the site's founders and holy figures. Cross-slabs, flat stones carved or incised with crosses and sometimes inscriptions, were a common feature of early Irish monastic cemeteries; they served as grave markers and devotional objects simultaneously. The socketed stone here belongs to a related tradition, providing a base from which a freestanding cross, most likely of stone or wood, could be raised above the grave of someone deemed worthy of particular commemoration. That the cross itself is gone leaves the function of the base oddly legible, its purpose written into the geometry of the void.