In 1993, during routine harvesting at Lackanamona, the ground gave way to reveal an opening roughly a metre across and nearly a metre deep, the mouth of a souterrain that had lain undisturbed beneath the tillage. Souterrains are underground stone-lined passages or chambers, built during the early medieval period and associated with nearby settlements, most likely used for cool storage or as places of refuge in times of threat.

The opening is not the whole picture. A narrow passage, just ten centimetres wide, appears to extend from it towards the southeast, suggesting that what was exposed is only the entrance to something more substantial still buried beneath the field. The souterrain sits approximately 140 metres to the northeast of a ringfort, that familiar circular enclosure of the early medieval Irish landscape, and the proximity is unlikely to be coincidental. Souterrains are frequently found in direct association with ringforts, often connected to them by underground tunnels, and the pair at Lackanamona fits this well-established pattern, even if the full extent of the underground structure remains unexcavated and unmapped.