It measures roughly seven and a half metres along its longer axis and half a metre in depth, and what it represents, if current thinking holds, is a roof that gave way long ago. Beneath it, or what remains of beneath it, may once have been a souterrain, an underground stone-lined passage or chamber built in early medieval Ireland, typically for storage, refuge, or both.

Souterrains are almost always found in close association with raths, the circular earthwork enclosures, bounded by banks and ditches, that served as farmsteads across Ireland from roughly the sixth to the twelfth centuries. This one sits in the slightly raised south-western quadrant of just such a rath, a positioning that would have made practical sense, keeping any underground structure on drier, better-drained ground. The randomly protruding stones visible at the surface are consistent with what happens when the capstones or corbelled roof of a souterrain collapse inward over centuries, leaving a telltale scar in the ground above. The qualification matters though: this feature is recorded as a possible collapsed souterrain, not a confirmed one. The depression could have other explanations, and without excavation the question remains open.