The carvings are not large or dramatic; the decorated surface measures less than 70 centimetres across, and the motifs themselves, cup-and-ring marks, are weathered enough that lichen cover makes them easy to miss entirely. Cup-and-ring marks are among the most widespread yet least understood forms of prehistoric rock art in Europe, consisting of a shallow circular hollow, the cup, surrounded by one or more incised concentric rings. What was meant by them, whether territorial, ritual, astronomical, or something else entirely, remains genuinely unresolved.

This particular boulder is one of a cluster of six decorated stones occupying a remarkably compact area of hillside, roughly 16 metres by 8 metres, on a south-facing slope at about 250 metres above sea level, overlooking the Kealduff River valley. The boulder itself is fractured sandstone, partly earthfast, with its carved surface oriented to the north. The decoration includes a probable single cupmark clearly defined across the upper portion, and two cup-and-ring motifs, each with a central cup approximately 4 centimetres in diameter and a surrounding ring about 2 centimetres wide. The depths of the carvings are slight, some only 3 millimetres, which, combined with weathering and lichen growth, gives the whole surface a faint, half-erased quality. A closely related carved outcrop sits just 20 centimetres to the north-east, and Lough Brin lies to the east. The concentration of decorated stones in such a small area is what makes Derrynablaha particularly notable; the site was documented as part of the wider archaeological survey of South Kerry published by Cork University Press in 1996.