Folklore across Ireland has a habit of attaching the label "Dermot and Grania's Bed" to megalithic monuments, the logic being that the eloping lovers, fleeing the wrath of Fionn Mac Cumhaill, needed somewhere to sleep each night, and there were conveniently thousands of ancient stone structures to accommodate them. The name appears on Ordnance Survey historic mapping for this particular site in Moymore, which tells you something about how long the association has been locally held. The monument itself is a wedge tomb, a type of megalithic burial structure common in the west of Ireland and typically dating to the late Neolithic or early Bronze Age, roughly 2500 to 2000 BC. The defining characteristic of wedge tombs is their gallery, wider and taller at one end and tapering toward the other, formed by upright slabs called orthostats and covered by large flat capstones.

The Moymore example measures roughly 4.8 metres along its northeast to southwest axis and 2.7 metres across, and its condition reflects several thousand years of slow structural negotiation. One substantial orthostat on the southeast side remains perfectly upright, standing 0.91 metres high and 2.1 metres long, a good indication of how the monument was originally constructed. The northwest side has fared less well; two parallel orthostats there have fallen outward, possibly because the main capstone, which covers the northeastern portion of the tomb, does not bear down on the largest southeast stone as it should, leaving the opposite side without the counterbalancing pressure that might have kept it stable. A second, smaller capstone covers the southwestern end, and the orthostats beneath it have collapsed inward under its weight. A third capstone-like stone lies displaced against the southwest end, apparently no longer in its original position. Ruaidhrí de Valera and Seán Ó Nualláin recorded the monument in their 1961 Survey of the Megalithic Tombs of Ireland and described it in terms that match what can be seen today, suggesting relatively little has changed in the intervening decades. The whole structure sits within a cluster of mature thorn trees, which marks the spot clearly in the surrounding improved pasture but also means that briar growth at the northeastern end obscures part of the monument from view.