Roughly 45 metres across, it presents itself as a ringfort, one of the thousands of circular enclosures built across Ireland during the early medieval period as farmsteads or defended homesteads. But something about its layout gives archaeologists pause.

A standard ringfort is typically defined by a bank and an external fosse, which is simply a ditch dug around the outside of the enclosure for drainage and defence. What makes the Balnavine site unusual is the possible presence of an internal fosse as well, a ditch running along the inside of the bank rather than the outside. That arrangement is more commonly associated with ceremonial or burial monuments than with domestic settlements, and it raises the quiet possibility that this earthwork was never a farmstead at all, but something older or stranger in purpose. A slight depression near the centre of the interior may represent the ghost of a house site, though that reading too remains tentative. The difficulty is practical as much as interpretive: the whole site is heavily overgrown with blackthorn, the dense, thorny scrub that colonises neglected earthworks across Ireland and makes close examination difficult. Whether the inner fosse is really there, or whether the uneven, sloping interior is simply playing tricks, cannot be confirmed without clearance work.