It is easy to overlook, particularly against the drama of the surrounding seascape, but what lies here is a prehistoric cairn, a type of burial or memorial monument built from heaped stone rather than earthen soil, and its presence on this remote Dublin island raises more questions than the landscape readily answers.

The cairn measures thirteen metres in length, nine and a half metres in width, and rises just over a metre above the outcrop. Unlike many cairns of comparable age elsewhere in Ireland, there are no kerbstones visible here; kerbstones being the upright slabs that typically line the outer edge of a cairn to retain its shape and define its boundary. Their absence may suggest the monument has been significantly disturbed over time, or simply that this was always a plainer, less formal construction. To the south-east of the main mound, there is an artificially raised area measuring twelve metres by eight metres, which may represent cairn material that has spread or been displaced from the original structure. The site was recorded by Geraldine Stout and uploaded to the national record in August 2011.

Lambay Island lies roughly three kilometres off the coast near Rush in north County Dublin and is privately owned, which means access is restricted and cannot simply be arranged on a whim. Visitors who do reach the island, whether by prior arrangement or as part of an occasional organised visit, should be prepared for terrain that rewards careful footing rather than speed. The cairn sits above Talbots Bay on the western side, so approaching from that direction gives the clearest sense of its position relative to the water below. The low profile of the mound means it does not announce itself at a distance; the slightly raised ground to the south-east is worth noting as a feature in its own right, since that spread material, if that is indeed what it is, hints at how much the original monument may have shifted from whatever form it once held.