The stone is freestanding, slightly rough and fractured, and barely reaches knee height across most of its length, rising to about 1.2 metres at its southern end. What makes it quietly arresting is that someone, at some point long before any written record, thought to leave an impression here, in this specific spot, on this particular face of rock, within a few metres of a small watercourse draining down from Coomnacronia Lake and close to what was once a bog trackway.

The decoration on the boulder's broadly flat, rectangular upper surface belongs to a tradition of prehistoric rock art found widely across Atlantic Europe, typically assigned to the Neolithic or Bronze Age periods. The motifs carved here include a single small cupmark, a shallow circular depression pecked into the stone, and a possible second cupmark at the northern end where weathering has made interpretation difficult. More elaborate is a partial cup-and-ring motif, a central cupmark encircled by a carved ring, measuring roughly 24 centimetres across. The ring survives only through its southern arc, running from the east-northeast around to the west-northwest, with the northern portion lost, most likely to the same weathering processes that have worn the entire surface faint. Two curving lines of pickmarks, one roughly 19 centimetres long and another about 11 centimetres, suggest further deliberate marking of the stone. There is some evidence that the decorated areas may have been prepared or smoothed before the motifs were cut, though centuries of freeze-thaw action have left that conclusion uncertain.

The boulder is not a grand monument in any conventional sense, and approaching it requires navigating open mountain heath. A small stone placed adjacent to the southeastern side serves as a natural step up, which suggests the decorated surface was always intended to be looked down upon rather than confronted face-on. The surrounding landscape, mountains rising to the south and west, the valley dropping away to the northeast, gives some sense of how deliberately this boulder may have been chosen for its position, even if what that choice once meant is now beyond recovery.