It is a souterrain, a type of man-made underground structure built during the early medieval period in Ireland, typically consisting of one or more chambers and connecting passages constructed from drystone walling and large capstones. These structures are found across Ireland in considerable numbers, though their precise function is still debated; they were likely used for cold storage, as places of refuge, or both. The Kerry landscape holds many such features, often hidden beneath ringforts or scattered across farmland with little to mark them at the surface.

The souterrain at Lissooleen is a recorded archaeological monument, meaning it has been identified and catalogued as part of Ireland's inventory of protected sites. Beyond that formal recognition, detailed information about this particular example, its dimensions, construction, associated features, or excavation history, has not yet been made publicly available. What can be said is that Kerry's early medieval communities were active builders of souterrains, and the presence of one at Lissooleen fits into a broader pattern of rural settlement and land use stretching back over a thousand years. The name Lissooleen itself likely derives from the Irish, with "lios" referring to a ringfort or enclosure, the kind of settlement with which souterrains are most commonly associated.