Not lost exactly, but absorbed. The vegetation has done what centuries of agricultural clearance and amateur excavation so often do to other sites in reverse, concealing rather than exposing, leaving no visible surface trace of what lies beneath.

A souterrain is an underground stone-lined passage or chamber, typically constructed during the early medieval period in Ireland, and associated most commonly with ringforts, the circular enclosed settlements that once defined the rural landscape. They served various purposes, most likely storage and refuge. This particular example sits in the north-western quadrant of a ringfort, a placement that is not unusual; souterrains were frequently built into the interior edges of such enclosures, tucked against the bank where the earthwork itself could form part of the structure. The ringfort at Mohanagh is recorded, the souterrain is recorded, but the ground gives nothing away to the casual eye.