It is not particularly dramatic to look at, reaching only about a metre in depth, yet its geometry is deliberate and its purpose was once anything but passive.

The hollow is a souterrain, an underground passage or chamber cut into the earth and typically lined or roofed with stone. Souterrains were constructed throughout early medieval Ireland, usually in association with ringforts, the circular enclosed settlements that were the dominant farmstead type from roughly the sixth to the twelfth centuries. Scholars debate their precise function, though storage of perishables, refuge during raids, and simple concealment have all been proposed. The Liscune example follows a two-armed plan: a longer axis of seven metres running east to west, and a shorter arm of six metres turning north to south. That right-angled arrangement is characteristic of the type and would have made the interior difficult to search quickly, which may well have been the point. Its parent ringfort, recorded under the site reference GA073-108, survives alongside it.