These are cupmarks, among the most enigmatic of all prehistoric carvings: simple, bowl-shaped depressions pecked into rock by hand, found across Ireland, Britain, and much of Europe, yet with no settled explanation for what they meant or what they were for. That the marks survive here at all, on a stone nearly three metres long, resting quietly in pasture with a view out over the harbour, gives the place a quietly unsettling quality.

The stone's situation is itself unusual. Rather than lying directly on the ground, it rests on another large stone, which is in turn propped up by smaller pad stones beneath. This arrangement caught the attention of William Copeland Borlase, the Cornish antiquarian whose 1897 work on dolmens of the British Isles documented megalithic structures across Ireland and beyond. He recorded this stone as a dolmen, the term then commonly used for a portal tomb, where a large capstone is raised above upright supports. Whether the current configuration is original or the result of later disturbance is not recorded, but the possibility that this cupmarked slab once functioned as a capstone, with the carved surface facing skyward, adds another layer of uncertainty to an already puzzling monument.