The structure here is a souterrain, a type of underground passage cut or built into rock, commonly associated with early Irish settlement sites and used variously for storage, refuge, or ventilation. What makes this one quietly unusual is that its builders did not simply excavate their own space and stop; they guided the tunnel directly into a pre-existing natural cave, as though the geology itself had been planned into the design.

The souterrain is cut from rock and follows a slightly dog-legged course, running north to south for roughly 3.2 metres before turning northwest for a further 2.5 metres, at which point a collapsed lintel blocks the way and the natural cave begins beyond it. The northern to southern section is now partially unroofed, its original lintel stones scattered and displaced, and loose rubble has accumulated inside. The northwestern arm survives in better condition, still roofed by several of the flat stones laid across it by whoever built the thing. The cashel it sits within, a cashel being a dry-stone ringfort enclosure, adds another layer of early medieval context to the site. Ordnance Survey maps from both 1840 and 1916 label the feature simply as 'Cave', which suggests that local knowledge of the natural opening persisted across generations even as the engineered passage leading to it was gradually forgotten or obscured.