By 1985, just two years after it was first recorded, no surface trace of it remained visible at all. Yet in May 1983, surveyors had found their way down into an L-shaped souterrain, a roofed underground passage of the kind built in early medieval Ireland, typically for storage or refuge, its entrance marked only by a cracked roof lintel.

The souterrain was drystone-built, meaning constructed without mortar, using carefully arranged stone to hold its shape, and it ran to more than 7.4 metres in length across two chambers. The first chamber, oriented east to west and measuring roughly 7.4 metres long, 1.7 metres wide, and 1.8 metres high, was accessible when surveyors entered. A second chamber extended from its north-west end, turning to run north to south, but it was choked with rubble and could not be entered. The whole structure sits within what may be the remains of a rath, a circular earthwork enclosure associated with early medieval settlement, suggesting the souterrain was once part of a farmstead or small defended residence. The combination of the two features is not unusual in itself, souterrains are commonly found within raths across Ireland, but the speed with which this one disappeared from view gives it a particular quality. Whatever collapse or infill occurred between 1983 and 1985 erased even the slight surface depression or hollow that might otherwise catch a passing eye.