It looks, at first glance, like little more than a collapse in the ground. What it actually marks is the blocked entrance to a souterrain, an underground passage or chamber typically constructed during the early medieval period, often beneath or beside a ringfort, and used for storage or as a place of refuge.

The souterrain itself is now inaccessible, its throat choked with rubble, leaving only this hollow as evidence that something lies beneath. Ringforts, the circular enclosures defined by earthen banks or stone walls that dot the Irish countryside in their thousands, frequently incorporated souterrains as part of their design. The association here at Rausakeera follows that pattern, with the underground feature positioned within the ringfort's interior. Beyond the loose stone and the dip in the ground, the full extent of the passage below remains unknown.