The stone, which measures roughly half a metre across, looks at first glance almost like a seat; it is fractured and weathered, with a roughly rectangular face on its south-westerly side where the decoration is clearly visible. That decoration is precise and deliberate: a central cup-shaped hollow enclosed by concentric rings, surrounded in turn by a collar of smaller cupmarks, the whole composition contained within a further outer ring that is broken at top and bottom, most likely by centuries of freeze-thaw damage to the stone.

Cupmarks are among the most widespread and least understood marks left by prehistoric people across Atlantic Europe. They are simple hemispherical depressions pecked into stone, and when combined with encircling rings and radial lines, as at Derrynablaha, they form a repertoire that appears from Kerry to Scotland to northern Spain. Scholars Shee and O'Kelly, writing in 1971, identified close parallels for this particular motif across all three regions. They were specifically responding to a theory put forward by Coles in 1965, who argued that the cup-and-ring pattern was a representation of a Late Bronze Age shield, complete with its characteristic concentric bosses. Shee and O'Kelly rejected this interpretation, and the broader question of meaning remains open. The Derrynablaha slab sits at around 246 metres above sea level and abuts a larger panel of rock art nearby, suggesting this was not an isolated act of mark-making but part of a sustained, perhaps accumulated, engagement with the landscape over time.

The site sits on the Iveragh Peninsula, the same mountainous terrain that carries the Ring of Kerry road around its perimeter, though Derrynablaha itself lies well away from that circuit, in upland ground that rewards careful navigation rather than casual passing. The rock art is described as clearly visible on the south-westerly face of the stone, and the upper surface may carry at least one additional cupmark, though this is less certain.