First recorded on the 1849-50 Ordnance Survey map, this feature consists of a large stone slab measuring 3.7 metres long and up to 2.3 metres wide, resting on three low supporting stones about half a metre above the rocky ground. The slab, which narrows from south to north and tilts slightly upward at its northern end, occupies a prominent position on a narrow ridge of bare rock in the townland of Oughterlin.

What makes this structure particularly intriguing is the ongoing debate about its origins. Whilst it bears a superficial resemblance to a megalithic tomb, experts have definitively ruled out this possibility. Whether the arrangement is entirely natural or represents some form of human intervention remains uncertain, though the careful positioning of the massive slab on its supporting stones suggests at least some degree of deliberate placement. The mystery deepens when considering two similar features located approximately 30 and 60 metres to the south; large boulders that appear to have been deliberately propped upright on smaller stones, creating a peculiar alignment of three stone structures along the ridge.

Despite being mistakenly catalogued as megalithic tombs in the 1987 Sites and Monuments Record for County Donegal, these structures have since been reclassified. Various antiquarians and archaeologists have documented the site since the mid-19th century, including detailed plans by Boyle Somerville in 1909 and sketches from 1929, yet the true purpose and origin of these unusual stone arrangements continue to elude definitive explanation. They remain as testament to the complex relationship between natural geological formations and human activity in Ireland’s ancient landscape.