Erosion has exposed an oval spread of limestone flakes, roughly three metres by two, sitting in the surface of a dune system that is itself in the process of disappearing. Alongside it, the steep faces of the dunes reveal a blackish layer that is thought to represent the remains of hearths, places where people once lit fires and stayed long enough to leave a mark in the ground.

A midden is essentially a rubbish deposit left by earlier inhabitants, most commonly consisting of shells, animal bones, ash, and domestic debris that accumulated over years or generations of use. They are among the more intimate kinds of archaeological site, less ceremonial than a megalith, less martial than a fort, and concerned instead with the everyday rhythms of eating, cooking, and discarding. The Fínis site is not alone on the island. A shell midden at the north-eastern end was recorded separately, suggesting that the island supported more than one focus of human activity at different points or perhaps simultaneously. Scholar and writer Tim Robinson noted the blackish hearth layer in 1985, and the limestone spread was documented in Paul Gosling's archaeological inventory of West Galway, published in 1993. The precise date of the original occupation has not been established from the available record, leaving the site in an intriguing kind of suspension, clearly visited, clearly used, but not yet fully deciphered.