It is not large. It tapers slightly as it descends, from just under three quarters of a metre wide at the top to a little under two thirds of a metre at the base, and stands nearly one and a half metres tall. What makes it worth pausing over is the precision of its carving: a Latin cross rendered in two incised lines, the angles between the arms hollowed out, and the two lower angles finished with wheel shapes, giving the impression of a cross that is almost pinned in place by its own geometry. Horizontal lines divide the space between the shaft and the surrounding panel into compartments, a detail that rewards a close look.

The scholar R. A. S. Macalister recorded the slab in 1916 to 1917 and placed it as twelfth-century in type. Cross-slabs of this kind, flat stones incised with a cross rather than carved in full relief, are a recurring feature of early Irish monastic sites, and Inishcaltra was certainly a well-established one. The island, also known as Holy Island, was associated with St. Caimin himself, a seventh-century figure, and the church that bears his name was part of a larger monastic complex that continued in use across several centuries. A twelfth-century attribution for the slab places it in a period of considerable ecclesiastical reorganisation in Ireland, when older monastic communities were being reshaped by continental influences and new church structures. The wheeled angles on the lower arms of the cross are a specific stylistic feature, suggesting the carver was working within a recognisable decorative tradition rather than improvising.