It measures twenty metres long and just over ten metres wide, runs on a north-west to south-east axis, and drops to a depth of nearly one and a half metres. Its flat bottom and regular shape give it the look of something deliberately made, and at its north-western end an entrance-like gap opens through the scarp, the raised earthen bank that defines the edge of the enclosure. Stone is visible in the sides of the depression, but no structural remains survive to settle the question of what this feature actually is.

The uncertainty itself is the most interesting thing here. A souterrain is an underground passage or chamber, typically stone-lined, built during the early medieval period as a place of refuge or cool storage, and often found within ringforts, which were the enclosed farmsteads of early Christian Ireland. The shape and position of this hollow would fit that interpretation reasonably well. But the same evidence could support a more mundane reading: a quarry pit, dug to extract stone for the construction of the ringfort itself. Without excavation, neither reading can be confirmed or ruled out. The feature sits in an interpretive limbo, recorded but unresolved, which is rather common for the quieter corners of the Irish archaeological landscape.