What collapsed into view was a souterrain, an underground passage or chamber typically cut from earth or lined with stone, built during the early medieval period and usually associated with a nearby ringfort. The chamber was described by those present as roughly six feet deep and three yards in length, with a rounded roof. It had been there, sealed beneath the soil, for perhaps a thousand years before the land above it finally lost the will to hold.

The souterrain sits within what was once a ringfort, though the fort itself has since been levelled and leaves no obvious mark on the landscape. Ringforts were the enclosed farmsteads of early medieval Ireland, typically circular areas bounded by earthen banks, and souterrains were often dug beneath or beside them, likely for storage or refuge. At Maulnagirra, both structures have effectively disappeared from view. After the 1975 collapse revealed the chamber, it was backfilled, and today there is no visible surface trace of either the souterrain or the ringfort that once enclosed it. What remains is essentially a coordinate, a patch of West Cork ground that holds more than it shows.