The island is a crannog, a type of man-made lakeshore or lake dwelling built in Ireland and Scotland from the Bronze Age through to the early modern period, often raised on timber piles and brushwood, and typically associated with high-status occupation. That a house should have stood on such a feature is not unusual in itself; that this one survives to any meaningful height, in a form legible enough to measure and describe, makes it quietly remarkable.

The structure is roughly rectangular, measuring about 5.8 metres east to west and 4.7 metres north to south, with walls averaging nearly a metre thick and standing to a height of around 1.3 metres in places. It was built without mortar, the stones simply laid and fitted against one another, a technique common across medieval Irish vernacular building. A narrow gap of about half a metre on the south-west side served as the entrance. Researcher D. Curley, writing in 2021 as part of a multidisciplinary study of later medieval Uí Maine, identified the structure and suggested it may originally have been roofed. The broader study concerned the Ó Cellaig, a powerful Connacht dynasty whose territorial centre, or cenn áit, may have been located in this part of east Galway, lending the crannog and its building a possible political as well as domestic significance.

The crannog sits at the centre of the lough and is described as tree-covered, which means the vegetation itself now forms part of the archaeology's character. The walls, though roofless and long abandoned, remain standing to a height that would make them visible to anyone who reached the island, though the water and the trees together ensure it stays largely out of sight from the surrounding land.