One slab sits near the centre of the enclosure; a second lies about six metres to the west. Between them, they are said to mark the entrance and a section of collapsed tunnel belonging to a souterrain, the kind of stone-lined underground chamber that farmers and communities in early medieval Ireland used for storage and, possibly, refuge.

The souterrain sits within a rath, the circular earthwork enclosure, defined by banks and ditches, that was the typical farmstead of early medieval Ireland and which appears throughout Kerry in considerable numbers. What local accounts preserve about this particular example is specific enough to be interesting: the passage was reached by descending stone steps, its walls were formed from clay rather than the more usual dry-stone construction, and the roof was made from large flat slabs laid across the top. That combination of earthen walls with a slab-built roof is relatively unusual and suggests a structure adapted to local materials and conditions. The collapse of part of the passage, which is what the western slab now marks from above ground, means the full extent of the underground space is no longer accessible or clearly known.