The socket, nearly a metre in length and only fifteen centimetres wide, is the kind of slot made to receive the tenon at the base of a standing stone cross, and the stone is now understood to be, or to have been, a cross-base. What makes it quietly puzzling is a slight dip worn into the eastern side of the socket, a detail that suggests long use or the particular way weight was once distributed against it. The cross itself, if there ever was one seated here, is gone.

When the antiquarian R. A. S. Macalister surveyed and published his plan of the graveyard in 1916 and 1917, he recorded a feature at this location and assigned it the number 13 on his plan. Later measurement placed the stone at 9.16 metres from the southern wall of the graveyard and 9.57 metres from the eastern wall, which does not quite match where Macalister marked it, and its orientation also differs from what his plan suggested. Small discrepancies of this kind are not unusual across a century of recording, but they are a reminder that early surveys, however careful, were working without the precision of modern measurement, and that stones on island sites can shift, be moved, or be misidentified across generations of scholarship. Inis Cealtra itself is a site of considerable early medieval significance, an island monastery associated with Saint Caimin, and the Saint's graveyard is one of several distinct enclosures within its monastic complex.