A cashel is a stone-walled ringfort, a type of early medieval farmstead enclosure common across Ireland, and this one holds what appears to be the collapsed remains of a souterrain. A souterrain is an underground passage or chamber, typically stone-lined or rock-cut, associated with early medieval settlement sites across Ireland and Scotland. They were used variously for storage, refuge, or both. This one, if that is indeed what it is, has caved in on itself, leaving a surface trace rather than an accessible tunnel.

The depression runs roughly 78 metres in length and around 3 metres wide, which gives some sense of the scale of what may lie beneath. It extends northward from the centre of the cashel's interior, suggesting it was deliberately positioned in relation to the enclosed settlement above. The qualification matters here: the word "may" does real work in the description of this feature. The ground has not been excavated, and the depression could result from other causes. What makes it worth attention is precisely that ambiguity, the long scar in the earth that hints at something built and then forgotten underground, surviving only as a subtle change in the landscape's surface.