It is a small, unremarkable-looking thing. But on its upper surface, now sitting roughly twenty centimetres lower than the rock it once belonged to, someone carved a series of symbols that have outlasted almost everything else we might know about them.

The carvings are cup-and-ring motifs, a form of prehistoric rock art found widely across Atlantic Europe and particularly concentrated in parts of Ireland, Scotland, and northern England. The basic form is exactly what it sounds like: a shallow circular depression, or cup, surrounded by one or more incised rings. At Drom, there are approximately five such motifs on a surface measuring around 1.3 metres north to south and just under 0.6 metres east to west. Two of the motifs have radial grooves running towards the south-west, a feature sometimes interpreted as a channel leading away from the central cup. One of these is a cup-and-two-ring motif about 13 centimetres in diameter, its outer ring cut short where the carved panel meets the edge of the stone closest to the parent rock. Towards the northern end of the decorated surface, which tapers to a near point, there is a smaller, slightly squarish cup-and-ring just 6 centimetres across. At the south-western corner, a natural-looking basin sits in the widest part of the panel. The eastern sides of the split rock are noticeably rougher than the smoothed and weathered upper surfaces, which may indicate that quarrying activity disturbed the stone at some point after the carvings were made. A low-lying rock immediately to the north carries no clearly visible art, though some indentations arranged in a roughly linear formation near its south-western end may be the traces of a picked line.

The carvings are difficult to make out in ordinary conditions. Heavy lichen encrustation covers much of the surface, obscuring detail that would otherwise be legible. Raking light, particularly in low sun at morning or evening, tends to be the most reliable way to read incised rock art of this kind, bringing out the shallow relief of the cups and rings against the surrounding stone.