Carved into the shaft of an incised cross is the dedication TOMAS AP[STAL], a shorthand invocation of Thomas the Apostle, lending the stone a specific devotional identity that most such slabs, which tend toward the anonymous, do not possess.

The slab is one of four cross-slabs now grouped around St Brecan's Grave in Eoghanacht, on Inis Mór. It was the antiquarian George Petrie who first recorded this particular stone in 1822, finding it inside Teampall Bhreacáin, the early church associated with the sixth-century saint Breacán. The slab itself is modest in scale, roughly 82 centimetres tall, 38 centimetres wide, and 12 centimetres thick. What it lacks in size it compensates for in craft: the cross is of the potent form, meaning each arm terminates in a crossbar, and the four quarters formed by the arms are filled with ornamented rolls, small decorative curved elements that give the surface a careful, considered quality. The cross rises from a roughly rectangular base, a compositional feature common to insular early Christian stonework. The Thomas dedication, abbreviated in the Latin manner, suggests the slab may once have marked a site or altar with a particular apostolic association, though the precise circumstances of its original placement remain unclear.