A souterrain, to give it its proper name, is an artificial tunnel or chamber built beneath the earth, typically during the early medieval period in Ireland. They are found associated with ringforts across the country and are thought to have served as places of refuge, cool storage for foodstuffs, or both. At Kilmoylerane, the passage itself has long since collapsed or silted over, leaving only these surface dips as a quiet trace of its existence.

The ringfort with which this souterrain is associated sits just to the north, and it is within that enclosure that the two depressions are located. Ringforts, the most common surviving monument type in the Irish landscape, were typically circular enclosures defined by an earthen bank and ditch, used as farmsteads during the early medieval centuries. The presence of a souterrain within one is not unusual in itself, but the collapsed state of the Kilmoylerane example means that what survives is more suggestion than structure, a faint legibility in the ground rather than anything you could easily read as architecture.