It sits where a souterrain once opened, a souterrain being an underground stone-lined passage, typically built during the early medieval period as a place of refuge, storage, or concealment. The entrance to this one was blocked up during relatively recent field-clearance operations, filled in with stones and soil, and what had been known locally as a 'cave' effectively vanished from view.

The passage reportedly ran on a north-to-south axis, though surveyors were only able to trace it for about one and a half metres to the north of the blocked entrance before losing it entirely. That brevity of record is itself telling: the souterrain may extend further underground, its full length now inaccessible and unmeasured. The lintel-like stone left at the surface, presumably a structural element from the original passage roof or entrance frame, is the only physical evidence remaining above ground. How old the structure is, who built it, and what its original purpose was in this particular field in North Galway remain unanswered questions.