At either end of the ridge, openings lead into what was once a souterrain, an artificial underground passage or chamber cut into the earth and typically lined with stone, built during the early medieval period as a place of storage, refuge, or concealment. Both entrances are now inaccessible, and the surface topography hints at additional chambers lying sealed beneath the grass.

The souterrain sits in the north-eastern corner of a ringfort, the circular earthwork enclosure that would have been the farmstead of an early Irish family, most likely sometime between the sixth and tenth centuries. The pairing is common enough across Ireland, ringforts and souterrains tending to occur together, with the underground structure tucked inside or at the edge of the enclosing bank. What gives this particular example a quiet distinctiveness is the ridge itself, a visible feature roughly ten and a half metres long that preserves the outline of the underground work even as the passages below remain shut to investigation. The site was recorded as part of a local archaeological survey of the Ballinrobe district, covering the areas around Lough Mask and Lough Carra, published in 1994.