That mixture alone sets it apart. Whatever this feature once was, it accumulated through human activity rather than simple geology, and its contents point to a place where people processed food, worked stone, and left behind the residue of daily or ritual life over an extended period.

What survives is partly structural and partly ambiguous. A thick revetted drystone wall, meaning a wall built with a facing of stone to hold back or define a mass behind it, curves from west through north to north-north-east, reaching up to five metres in width and around 1.2 metres in height at its tallest point. It appears to enclose an area to its east. Along the eastern and south-eastern sides of the field, a steep natural slope or scarp may continue the same line, suggesting that topography and construction were deliberately combined. To the south and south-west, the enclosure seems to resolve into a large, ill-defined oblong mound running roughly east to west, measuring around sixteen metres across and rising to about 1.7 metres at its highest. The archaeologist and writer Tim Robinson noted the feature in 1980, and it was subsequently recorded in the Archaeological Inventory of County Galway, compiled by Paul Gosling and published in 1993. Whether the structure represents a domestic enclosure, a midden accumulation, a small ringfort-like feature, or some combination of these functions remains unresolved. Inis Oírr has been inhabited for millennia, and the island's thin limestone landscape tends to preserve and compress evidence in ways that make clear categorisation difficult.