At two metres wide and just sixty centimetres thick, the stone has a broad, flattened profile, sub-rectangular in shape, more like a planted blade than a rounded boulder. It is the kind of object that rewards a second look, once you have registered that something this size does not end up standing upright in a field by chance.

Standing stones of this type are scattered across Cork and the wider Munster landscape, and while their precise purposes remain a matter of ongoing debate among archaeologists, they are generally associated with the Bronze Age, roughly 2500 to 500 BC. Some are thought to mark boundaries, burial sites, or routeways; others may have served astronomical or ceremonial functions, their alignments possibly keyed to solar or lunar events. The northeast-southwest orientation of the Kilnagnady stone is a recurring feature among Irish standing stones, and while no single explanation covers all examples, that axis does correspond roughly to the directions of sunrise and sunset around the solstices. Whether that connection was intentional at this particular site is unknown, but it is not a detail easily ignored.