About three kilometres south-east of Renvyle, the remains of a portal tomb sit partly incorporated into an animal pen, its ancient stones repurposed by farmers who needed a wall more than they needed an archaeological monument. That pragmatic collision of the prehistoric and the pastoral is, in its own way, entirely typical of rural Ireland, but it does not make the site any less worth understanding.

Portal tombs, sometimes called dolmens, are among the earliest megalithic structures in Ireland, generally dating to the Neolithic period, roughly four to six thousand years ago. They are characterised by a burial chamber defined by tall upright portal stones at the entrance and one or more large capstones laid across the top. At Cloonlooaun, the chamber is aligned roughly north-west to south-east, with the entrance at the south-east marked by a tall portal stone set beside a doorstone. A sidestone, overlapping the portal slightly, leans outward to the south-west, and propped against it is a large upright slab that was probably once a roofstone, dislodged at some point from its original position. A second flat roofstone survives to the north-west, resting across another large slab. The north-east side of the monument has disappeared entirely, and an old field fence runs up to the entrance on that side, making it difficult to read the original layout with confidence. Precisely because so much has shifted or vanished, the classification as a portal tomb carries a degree of uncertainty, though the surviving elements are consistent with that form.