Beneath it, a small opening, roughly forty centimetres by twenty, leads into the ground, though it is now blocked with the accumulated rubble of field clearance. This is all that remains visible of a souterrain, an underground passage or chamber typically built during the early medieval period, constructed from stone and used variously for storage, refuge, or as an adjunct to a nearby settlement that may itself have long since vanished from view.

Souterrains of this kind are scattered across Ireland, but most are at least partially accessible or documented through excavation. This one at Cloghera More is noted as inaccessible, its entrance sealed not by deliberate preservation but by the slow accumulation of stones cleared from surrounding fields over generations. The upright slab, still standing, suggests someone once knew exactly where the entrance was, and may have used it as a marker. What lies beneath, how extensive the passage might be, and what period it dates to, cannot be said with certainty from surface observation alone.