It is not especially tall, measuring just 1.35 metres in height and roughly 80 by 64 centimetres across, with a subrectangular profile rather than the dramatically pointed silhouette many people associate with prehistoric standing stones. What makes it quietly compelling is precisely that ordinariness: a shaped but unhurried block of stone, placed with apparent deliberateness in relation to the landscape around it, the river to its west and the valley opening out ahead.

Standing stones of this kind are a familiar, if poorly understood, feature of the Irish countryside. They date broadly to the Bronze Age, though precise dating for individual examples is rarely possible without excavation, and their original purpose remains a matter of genuine uncertainty. Some appear to mark boundaries, burial sites, or routeways; others may have had astronomical or ceremonial significance, particularly where their alignment corresponds to features of the local topography or the movement of the sun. The northwest to southeast orientation of the Coolnagarrane stone, set beside a river valley running roughly north, could reflect any or all of these possibilities, and no excavation record exists to settle the question one way or the other.