A fulacht fia, the term used for a type of prehistoric cooking or industrial site, typically survives as a low horseshoe-shaped or circular mound of fire-cracked stone and charcoal-rich soil, the debris left behind from repeated cycles of heating stones and dropping them into water-filled troughs. At Glenleigh, even that modest physical presence has gone. There is no visible surface trace.

What survives instead is a cartographic ghost. A 1936 Ordnance Survey map recorded a small circular mound at this location, giving the site a documented existence even as the ground itself has since been levelled or eroded into the surrounding pasture. Fulachtaí fia are among the most commonly recorded prehistoric monument types in Ireland, found in their thousands and generally dated to the Bronze Age, though their precise function has long been debated, with suggestions ranging from communal cooking to hide-working or even brewing. The Glenleigh example is not alone in its field; a second fulacht fia lies immediately adjacent, which in itself is not unusual, as the sites often cluster near reliable water sources on low-lying or sloping ground.