Souterrains, as these structures are known, are dry-built tunnels typically associated with early medieval ringforts, thought to have served as storage chambers, refuges, or escape routes. What makes the Fahalea example quietly peculiar is its near-total disappearance, both physically and from public awareness.

The sole historical record of these passages comes from O'Leary, writing in 1918, who noted two souterrains connected with the lios, the Irish term for a ringfort enclosure, and mentioned that one of them had already been opened by that point. What that opening involved, who carried it out, and what, if anything, was found, he does not say. The ringfort itself survives as a recorded monument, but the souterrains have vanished from sight entirely, leaving only that single early twentieth-century reference to confirm they ever existed. It is a small, precise kind of erasure: not the dramatic collapse of a great structure, but the quiet subsidence of something that was never meant to be seen in the first place.