The slabs, each roughly two metres long, eighty centimetres wide, and forty centimetres thick, are the fallen lintels of what may be a souterrain, an artificial underground passage typically constructed during the early medieval period in Ireland, often used for storage or refuge. They lie oriented north to south, leading toward a stony mound that fills the northern interior of the enclosure, and it is that directional logic, slabs pointing purposefully toward a raised mass of stone, that gives the site its quiet intrigue.

A cashel is a roughly circular enclosure defined by a stone wall, a form of settlement common across Ireland from the early medieval period onward. The cashel here, recorded separately, provides the broader context for this possible souterrain. Souterrains were frequently built within or immediately adjacent to such enclosures, their entrances sometimes concealed and their interiors corbelled or lintel-roofed with the kind of substantial slabs now lying displaced at Carran. The dimensions of these lintels suggest a passage of some solidity in its original form. Whether the structure beneath is intact, partially collapsed, or entirely infilled remains uncertain; the classification as a possible souterrain reflects that the roof has fallen and no chamber has been confirmed.