It marks the entrance to an underground passage that almost no one can enter: the opening stands just twenty-four centimetres high, barely enough to admit a forearm. Beside it, a clochán, the drystone corbelled hut that was once the surface dwelling here, has been swallowed by a field clearance cairn, the kind of rough pile that generations of farmers built simply by dragging stones off workable ground. Together, the buried hut and the sealed underground passage give the site an oddly closed quality, as though it has been steadily pulling itself out of view.

The souterrain beneath the slab, a type of underground stone-built structure common in early medieval Ireland and often associated with storage or refuge, was recorded in some detail by R. A. S. Macalister in 1899. He found two chambers connected by a narrow creepway. The outer chamber ran WSW to ENE and measured three metres long by 1.2 metres high. The creepway between the chambers was just sixty centimetres high and thirty centimetres wide, tight enough to test even a determined person. Beyond it, the inner chamber ran NNE to SSW, three metres long and 1.5 metres wide. The whole structure was drystone built, meaning no mortar, just carefully fitted stone holding its own weight in the dark. J. Cuppage documented the site again in the 1986 Dingle Peninsula archaeological survey of Corca Dhuibhne, by which point the entrance had become the low slab-framed gap that makes access impossible today.

The slab protruding from the hillside is visible from the surface, and the field clearance cairn that has consumed the clochán is identifiable for what it is once you know to look. The souterrain itself cannot be entered, but the scale of Macalister's measurements gives some sense of what lies beneath: two stone rooms, aligned in different directions, connected by a gap a child would find tight.