It is the kind of thing that rewards patient looking: a low, sod-covered bank tracing a near-square shape, roughly 5.8 metres by 5.9 metres, with most of the eastern side worn away and a narrow gap of about 0.7 metres on the west that may once have served as an entrance.

The structure sits within a rath, a type of circular or oval earthen enclosure commonly associated with early medieval settlement in Ireland, where they typically served as enclosed farmsteads. The example here on Oileán Mionnán is recorded as MA003-009, and the possible house occupies its western interior. What date either feature belongs to remains uncertain; the island's remoteness has not made systematic study easy, and the evidence on the ground is slight. The details were recorded through fieldwork by archaeologist Michael Gibbons in October 2015, and what he observed was, by that point, already largely a matter of reading the landscape rather than any standing structure.