It is not especially large, roughly three metres by one and a half, and rises less than half a metre above the ground. What makes it remarkable is what someone carved into its surface, probably several thousand years ago: an elaborate arrangement of grooves, rings, and cup-marks that covers nearly the entire face of the stone, organised into zones and connected by channels in a way that feels deliberate, even systematic, though its meaning remains entirely unclear.

The carvings belong to a tradition of prehistoric rock art found across Atlantic Europe, typically dated to the Bronze Age, though some examples may be earlier. The vocabulary is consistent across vast distances: cup-marks, which are small hemispherical depressions pecked into the rock surface; cup-and-ring motifs, where one or more concentric rings surround a central cup; penannular rings, which are rings left deliberately open at one point; and radial grooves that extend outward from cups like spokes. At Gortnagulla, these elements are gathered into a series of large enclosed areas, oval, circular, and D-shaped, defined by broad grooves up to two and a half centimetres wide. Within these zones, the motifs are densely arranged: one cup-and-three-ring motif with penannular rings reaches thirty-two centimetres across, while six smaller rings cluster together at the south-western end of the surface. The whole composition was first noted in print by Lynch in 1906, and later documented in detail by A. O'Sullivan and J. Sheehan in their archaeological survey of the Iveragh Peninsula, published by Cork University Press in 1996.

The stone sits in mountain pasture with open views westward along the River Ferta valley to the sea. The decorated face is slightly weathered but the motifs remain well defined, visible as a network of grooves and pits across the sandstone. A low stone field wall runs roughly twenty metres to the west, a reminder that this landscape, however remote it feels, has been worked and divided by people across many generations.