The boulders, catalogued together under the monument reference DU026-145/147, bear cup-marks, which are shallow circular depressions pecked into stone by prehistoric people whose precise intentions remain unknown. What makes their presence quietly remarkable is the circumstance of their discovery: they came to light not through dedicated fieldwork, but because a motorway was being built through Carrickmines.

The boulders were uncovered during archaeological investigations carried out along the route of the South-Eastern Motorway, as recorded by Clinton in 2002 and 2004. One of the three, known as Rock B, was examined and described in detail by Dr Muiris O'Sullivan. It is a slightly rounded granite boulder with a convex face measuring 0.60 metres by 0.48 metres, roughly the surface area of a large chopping board. A fault line runs along the centre of that face for approximately half its length, and at least nine cup-marks are visible, generally clustered near the centre and arranged in two loose arcs, with a single outlier sitting apart from the group. Three of the marks fall along the fault line itself, which raises a genuine interpretive question: O'Sullivan noted that these three might conceivably be natural rather than human-made. The full excavation findings were published in a four-volume report compiled by T. Breen in 2012 on behalf of Dún Laoghaire-Rathdown County Council, the product of work carried out under ministerial directions and archaeological licences.

These boulders are not accessible as a standing field monument in the way that a megalithic tomb or a hillfort might be; they were recovered during a road scheme, and their current location and display status would need to be confirmed with the relevant county council or the National Monuments Service before a visit is planned. Anyone with a serious interest in the material would do well to consult the Breen 2012 report directly, which includes detailed drawings of the rock art. The cup-mark tradition in Ireland is widespread but poorly understood, and even a small cluster of nine marks on a worn granite face carries the same fundamental puzzle as the grandest decorated kerb stone: nobody knows with certainty what they meant to the people who made them.