Its walls drop as much as a metre below the surrounding ground level, so that from a distance it reads less as a ruin than as a shallow depression in the headland, easily mistaken for a natural feature of the rock-strewn shore. Beaches open out to the north-east and south-west, and the position, on a small promontory with water visible in two directions, suggests the building once had some deliberate relationship with the sea.

The structure is rectangular, measuring 4.2 metres north to south and 2.7 metres east to west, and is built from granite boulders. A gap of 0.7 metres at the northern end of the east wall marks where the doorway once stood. The east wall shows double-walling, a construction technique in which two parallel faces of stone are built together, giving a combined width of 0.6 metres; on the other walls, only the inner face remains visible above ground. About 20 metres to the south-east stands a ruined house built by the Congested Districts Board, the late nineteenth-century body established to improve conditions in the poorest and most overcrowded parts of rural Ireland, particularly along the western seaboard. The relationship between the two structures is uncertain. The sunken building may have served the same household, perhaps as a store, a shelter for animals, or something related to fishing or kelp-processing, but its date and original function remain genuinely unknown. It was first recorded in April 2014, when Erin Gibbons brought it to wider attention.