They are thought to have served as places of refuge, storage, or concealment. The one at Gallaras, on the Dingle Peninsula in County Kerry, was not discovered through any deliberate excavation or antiquarian interest, but by accident, in 1979, when a mechanical digger removing a field fence broke through into something that had been sealed underground for centuries. The opening was too narrow to enter, and part of the chamber wall had to be removed by hand before anyone could get inside.

What the subsequent inspection revealed was a compact but carefully built structure. The oval chamber, measured at roughly 1.7 metres east to west and just 1 metre wide, had drystone walls, built without mortar, that inclined slightly inward from a foundation course of large blocks and were capped by two roofing slabs sitting about 0.9 metres above the floor. From the north-west corner, a low passage ran north-north-east, only about 0.46 metres wide and 0.6 metres high, before collapsing after roughly a metre. The floor of the chamber held a thin deposit of coarse silt, and scattered through it was charcoal, the usual ambiguous residue that archaeology so often turns up without clear explanation. The passage walls at the junction with the chamber were formed by upright slabs, with drystone construction continuing beyond. Nothing of the souterrain is now visible at ground level. What is suggestive, though, is a curving field boundary visible on the second edition Ordnance Survey map at this location, which may trace the outline of a much older enclosure around which this underground structure once sat, the souterrain's parent settlement long since erased from the surface.