The first edition of the Ordnance Survey six-inch map, produced in the nineteenth century, marks a small dot in the southern half of an earthwork enclosure and labels it simply "Cave". That dot represents a souterrain, an artificially constructed underground passage or chamber, typically stone-lined, which in early medieval Ireland served purposes ranging from storage and refuge to ritual use. The earthwork it sat within has also vanished from the visible landscape entirely.

The association between souterrains and enclosing earthworks is well established in Irish archaeology. Such earthworks, often the remains of ringforts or similar enclosed settlements, were the farmsteads of early medieval landowners and their households. A souterrain beneath or adjacent to the living area would have offered cool, stable conditions for storing food, or a place of concealment in times of danger. At Cloonee, both the enclosure and its underground feature have left no surface trace, meaning the ground gives no indication today of what the cartographers once recorded. The site survives only in that earlier map, a small dot marking the memory of something buried.