It only announces itself from the air, as a cropmark, the kind of subtle discolouration in a ripening crop that betrays buried ditches or banks below the surface. Roots grow differently over disturbed ground, drawing moisture unevenly, and in the right conditions that difference shows up in the colour or height of the crop above. On satellite imagery captured on 28 June 2018, this ring-ditch became legible in exactly that way.

The feature was identified and reported by Simon Dowling, who noticed it on Google Earth. A ring-ditch is typically the remnant of a prehistoric burial mound, or barrow, where the circular trench that once surrounded a central mound has survived underground long after the mound itself was levelled by centuries of ploughing. What makes Clomantagh particularly interesting is that this is not an isolated find. The ring-ditch sits among at least four others in the same area, along with a related enclosure, together forming what is likely a barrow complex, a cluster of burial monuments that would have been a significant feature of the prehistoric landscape here. Such groupings are known elsewhere in Ireland and often indicate that a locality held ceremonial or funerary importance over a long period.