What remains today is a rectangular hollow, roughly 16 metres long, four and a half metres wide, and up to one and a half metres deep, running north to south and flanked on either side by the earthen banks that were thrown up during that informal digging. The word "excavation" sits in quotation marks for good reason: whatever happened here was not an archaeological investigation in any formal sense, and the result is a site that has been disturbed without being understood.

A souterrain is a man-made underground passage or chamber, typically associated with early medieval settlement in Ireland, often built of stone and used for storage or refuge. Whether the feature at Moneen ever took that classic form is now genuinely unclear. The site is locally regarded as a "cave," and the folk tradition attached to it is particular: the passage is reputed to run underground all the way to a second ringfort, located about one and a quarter kilometres to the north-north-west. Subterranean tunnels connecting two forts are a recurring motif in Irish local memory, more often mythological than literal, though the presence of large stones and what were described as bones during the digging does suggest something was down there. No record was made of what those stones or remains actually were, and without that information the true character of the original structure remains open.