Others have effectively vanished, surviving only in memory and in the administrative record that follows a landowner's offhand remark. The fulacht fia at Ballysallagh, County Kilkenny, belongs firmly to the second category. It sits, or once sat, on a steep west-facing slope now given over to reclaimed grassland, and by the time anyone came to look for it formally, there was nothing to see at ground level.

Fulachtaí fia are among the most common prehistoric monument types in Ireland, typically appearing as horseshoe-shaped mounds of burnt and fire-cracked stone, the debris from repeated episodes of water-heating. The working theory, broadly accepted though still debated, is that water was brought to the boil in a trough by dropping in stones heated in a nearby fire, the cracked and spent stones then piled to the side over time. They cluster around wet ground and streams, and date mainly to the Bronze Age. At Ballysallagh, the landowner noticed what appeared to be such remains during land reclamation work, which involves clearing, draining, and often reseeding ground that had previously been rough or marginal. That kind of earthmoving can bring buried material to the surface, or equally can destroy and scatter it. When the site was subsequently inspected, no visible trace remained above ground, leaving open the question of whether anything survives below the surface of the slope.