What makes it quietly remarkable are the two shallow, circular depressions, known as cupmarks, that have been deliberately worked into its surface. Cupmarks are among the most enigmatic carvings in the prehistoric repertoire: found across Ireland, Britain, and much of Europe, they appear on standing stones, burial monuments, and loose boulders, yet their precise meaning or function remains unresolved. What we do know is that someone chose to place, or leave, a marked stone at the threshold of this enclosure.

The detail was recorded by Hartnett in 1939, who noted the stone lying on top of the stone gap at the ringfort entrance. A ringfort, to give the basic shape of it, is a roughly circular enclosure defined by one or more earthen banks or stone walls, typically dating to the early medieval period in Ireland, between roughly the fifth and twelfth centuries. They were most commonly used as farmsteads. Whether the cupmarked stone was already ancient when the ringfort was built, and was deliberately incorporated into the entrance, or arrived there later by chance, is not recorded. The combination of a prehistoric carved stone and an early medieval threshold does, however, invite the kind of speculation that archaeology tends to leave comfortably open.