It measures just fourteen metres across at its widest point and is edged by a collapse of loose stone, the degraded remains of what was once a cashel, the term used for a ringfort built from dry-stone walling rather than earthen banks. What makes it quietly puzzling is not its size but its interior: the ground rises towards the centre, and at the south-east end sits a circular platform of natural rock outcrop, roughly 6.7 metres in diameter, which may once have served as a habitation area. Whether that platform was shaped by human hands, or simply pressed into use because it was already there, remains unclear.

The site is classified as a cashel-type ringfort, a form of enclosure associated broadly with early medieval Ireland, though the degree to which this particular example was constructed or simply adapted from the natural island topography is an open question. A stone causeway, eight metres long and one metre wide, extends from the northern side of the island to a nearby natural island, suggesting that access and movement between the islands mattered to whoever used this place. At the south, a natural shelf of rock outcrop appears to have functioned as a landing place, giving the site a modest but legible infrastructure of arrival and departure. Paul Gosling, compiling the Archaeological Inventory of County Galway in 1993, noted the platform as enigmatic, and that word still fits: it is not obvious what it was for, or how much of what survives here is human work and how much is the lough's own geology wearing the appearance of intention.