When surveyors first recorded it in March 1983, the slab was lying flat on the grass to the south of the old church. By November 1988 it had been moved to where it stands today, set into the northwest corner of a low walled enclosure built against the church's southeastern gable. It is a quietly absorbing object, and easy to overlook.

The slab is 1.59 metres long and tapers from a width of 0.41 metres at the top down to just 0.15 metres at the base, with bevelled edges that give it a clean, slightly angular profile. Carved into its face is a two-line Latin cross, meaning the cross design is rendered with a double incised line rather than a single cut, a technique that gives the image a subtle sense of relief and weight. The head of the cross carries decoration that is now difficult to read clearly, but close inspection suggests that the arms bifurcate towards their terminals, splitting into two as they reach the ends, and that there may be a fleur-de-lis motif at the very top. The shaft runs the full length of the slab. This type of decorated graveslab is associated with medieval Irish ecclesiastical sites, where they marked individual burials within or close to a church, and the carving conventions, particularly the bifurcating arms, place it broadly within a tradition found across Connacht.

Roscam itself sits within an early ecclesiastical enclosure, the remains of a monastic or church settlement whose origins predate the Norman period. The ruined church the graveslab now leans against is part of that longer history, and the modern walled enclosure, though recent in construction, was clearly intended to give the slab some protection. The fleur-de-lis detail, if the reading is correct, hints at a later medieval date when continental decorative motifs had filtered into Irish stone carving, though the worn surface makes certainty difficult.