Most standing stones are broadly rectangular or roughly squared off, shaped by whatever the local geology offered and by the hands that levered them upright. This one, however, presents five faces to the surrounding hillside, and carries markings along its edge, the precise nature of which remains quietly tantalising.

The stone stands 1.7 metres tall and measures 1.3 metres by 0.5 metres at its base, oriented along an east-northeast to west-southwest axis. Such alignments are common enough among Irish prehistoric standing stones, often interpreted in relation to solar or lunar events, though no specific astronomical association has been documented for this particular example. It was a researcher named Myler who, writing in 1998, drew attention to the pentagonal shape and the edge markings, details that might easily be overlooked by a casual glance. Standing stones of this kind are generally understood to date from the Bronze Age, serving purposes that may have included territorial markers, ritual focal points, or memorials, though the archaeological record rarely supplies a definitive answer. The Coomleagh stone sits in working farmland, as many of these monuments do, quietly outlasting the fields drawn up around it.