What lies beneath is a souterrain, an artificial underground structure built from dry-stone walling and capped with flat roof lintels, of the kind constructed in early medieval Ireland as places of refuge, storage, or concealment. The collapse has left the interior partially exposed to the sky, and the visible stonework gives a clear impression of a single passage or chamber running roughly north-east to south-west, with the two openings sitting approximately four metres apart along that same alignment.

Souterrains of this type are fairly widespread across Ireland, though they are often found in close association with a ringfort or enclosed settlement. What makes this example quietly unusual is that no trace of any such enclosure survives nearby. Whether the associated settlement has simply disappeared or was never built in the conventional way is impossible to say. The hill itself sits above a stream gully that drops away to the south, with Carrowmore Lake visible roughly 750 metres to the north-west across the surrounding undulating ground. Just 25 metres to the south-west, on the far side of that same stream gully, lies a children's burial ground, a type of site known in Ireland as a cillín, where unbaptised infants and others excluded from consecrated ground were interred, often over many centuries. The proximity of the two sites may be coincidental, but it gives this particular hillside an unusually layered quality, two kinds of concealment, one underground and one social, occupying the same small patch of countryside.