The cross-slab, a flat rectangular stone incised with a large Latin cross and an early medieval inscription in the four quadrants around the cross's arms, was last reliably reported in the 1940s, and its present whereabouts remain unknown.

The slab first came to wider attention in 1802, when a Church of Ireland clergyman, Reverend James Little, found it in Kilcummin graveyard. The following year he published a drawing of it, along with what subsequent scholars charitably described as a fanciful interpretation of the inscription carved upon it. The inscription is written in Goidelic, the early form of Irish from which modern Irish and Scottish Gaelic descend, and the correct reading was eventually settled by the antiquarian George Petrie in 1878. He read it as OROIT AR ANMAIN MAC ETICH, meaning "Pray for the soul of Mac Etich", a formulaic prayer request of the kind commonly found on early Christian memorial stones throughout Ireland. The layout of the text is carefully arranged across all four quadrants of the cross, with the final line running across both lower sections simultaneously. Small equal-armed crosses punctuate three of the quadrants, integrated neatly among the letters. Little's published drawing, though inaccurate in its textual interpretation, does capture the slab's general form: a large Latin cross extending nearly the full length and width of the stone, with its terminals meeting grooved horizontal lines that most likely once formed a continuous frame running around the entire slab.

When the scholar R. A. S. Macalister visited Kilcummin in the 1940s while compiling his corpus of early Irish inscriptions, he could not find the slab at first. A woman passing through the graveyard told him she had seen it as a child and gestured towards a dense tangle of brambles growing against the outside of the south wall of the church. Whether the stone still lies there, or has since been moved, damaged, or buried more deeply, is not recorded. A second cross-slab, a separate monument altogether, does survive in the northern half of the same graveyard and can be seen there today.