It belongs to a category of structure that Irish archaeology calls a souterrain, an underground gallery built from dry stone, typically associated with early medieval ringforts and used variously for storage, shelter, or concealment. This one, attached to the ringfort recorded at the same site, has left no trace on the surface at all.

What little is known comes from a 1977 observation by McCarthy, who noted a collapse in the area of the farm buildings and recorded the basic dimensions: stone-built, somewhere between 1.2 and 1.5 metres wide, running on that north-north-westerly alignment. That partial glimpse into a subsurface structure is itself now the entire documentary record. The collapse McCarthy observed suggests the passage was already in poor condition by the time anyone thought to write it down, and subsequent visits have confirmed there is nothing left to see above ground. The ringfort to which the souterrain belongs, a roughly circular enclosure of the kind that dots the Irish countryside in the thousands, survives as a separate feature, but the underground component has effectively vanished into the soil and the weight of the farmyard above it.