A souterrain, to give the structure its proper name, is a hand-built underground chamber or tunnel, typically constructed from dry-stone walling and roofed with large flat slabs, and associated in Ireland with Early Christian period settlements, roughly the sixth to twelfth centuries. They were used variously for storage, refuge, or as ancillary spaces attached to ringforts and farmsteads. The one at Skarragh was stone-lined, which places it squarely within that tradition, but it belongs now to a category of archaeological sites that are, in a practical sense, gone.

Local information recorded around 1961 notes that the souterrain was found at that time and subsequently infilled. Whether it was uncovered accidentally during agricultural work, or investigated briefly before being sealed again, is not recorded. What is known is that it left no visible surface trace. The site exists on the archaeological record as a place where something once was, and where that something was encountered once, noted, and then put back out of sight.