Only on close inspection does it resolve into the remains of a subcircular hut, its walls scarcely breaking the surface of the surrounding bog. It measures roughly 2.2 metres by 1 metre, which is to say it is extremely small, even by the modest standards of early Irish shelter-building.

A subcircular plan of this kind is typical of the simpler vernacular structures scattered across the Irish uplands and boglands, built without mortar and sometimes used as seasonal shelters by those moving livestock to summer pastures, a practice known as booleying. The bog itself has done the work of preservation here, its acidic, waterlogged conditions slowing the decay of organic and stone material alike. The site at Crossderry was catalogued as part of the archaeological survey of South Kerry compiled by A. O'Sullivan and J. Sheehan, published by Cork University Press in 1996, which systematically documented the remarkable concentration of field monuments across the Iveragh Peninsula. That peninsula, running into the Atlantic between Dingle Bay and the Kenmare River, contains one of the densest archaeological landscapes in Ireland, much of it still lying quietly beneath the surface of the land.