It measures roughly 39 centimetres wide and 44 centimetres tall, not much larger than a sheet of paper, and its surface carries a Latin cross of a single incised line, the ends forked and slightly flared at the top and bottom, narrowing at the sides. The effect is deliberate and geometrically considered, a detail easy to walk past without registering what it represents.

The scholar R.A.S. Macalister recorded the slab in 1916 to 1917, classifying it as eighth-century in type, which places it in the early medieval period when Inishcaltra, known also as Holy Island, was an active monastic settlement on Lough Derg. Cross-slabs of this kind are among the more modest survivals of early Irish ecclesiastical life; rather than freestanding high crosses with their elaborate figurative carving, a cross-slab is simply a stone, often small, incised with a cross form and embedded into a wall or set upright in the ground. They marked sacred space, commemorated individuals, or indicated burial plots, though the specific purpose of any given example is rarely recoverable. The forked or expanded terminals on this cross are a recognised feature of the period, a stylistic convention seen across early Christian sites in Ireland.