This one in Coolagh, County Galway, leaves nothing at all to see. Somewhere beneath the ground to the south-west of a nearby rath lies what may be a souterrain, an underground stone-lined passage or chamber built during the early medieval period, typically for storage, refuge, or ventilation of an adjacent settlement. Whether it genuinely exists there is, in a sense, still an open question.

The only record of this possible structure traces back to a conversation with Dr J. Shiels in March 1981, passed on as local knowledge rather than the result of excavation or survey. No visible surface trace survives, which means the feature has never been confirmed through physical investigation. It sits in the record as a possibility, tied to the rath beside it, that earthwork enclosure of raised banks and ditches that would once have defined a farmstead or settlement in early medieval Ireland. The association makes sense in archaeological terms, since souterrains were commonly built within or adjacent to raths across Ireland, but sense and confirmation are not the same thing.