These are cupmarks, among the most enigmatic category of prehistoric rock art found across Ireland and Britain: shallow, roughly circular depressions ground or pecked into rock, typically a few centimetres across and no more than a centimetre or two deep. The three confirmed examples here measure between five and six centimetres in diameter, with a depth of one to two centimetres. Several other depressions nearby appear to be naturally formed, which is a common complication with cupmarked sites; distinguishing human work from weathering and geological accident is not always straightforward, and the boundary between the two can be genuinely ambiguous.

Cupmarks of this kind are generally attributed to the Bronze Age, though their purpose remains unresolved. They appear on standing stones, on the capstones of megalithic tombs, on exposed bedrock, and on loose boulders, and they occur with enough consistency across different cultures and periods to resist any single tidy explanation. Ritual use is frequently proposed, but whether that means offerings, boundary marking, astronomical observation, or something else entirely is a matter of ongoing debate. What can be said of the Kilcoe example is that its position is deliberate in feel: a south-facing slope on a heather-edged ridge, with a wide view over the bay below, is exactly the kind of elevated, oriented location where prehistoric communities across Ireland chose to leave their marks on the landscape.