The mound was levelled by farm machinery sometime in the 1950s, yet it refuses to disappear entirely. Beneath and around it, spread across an area of up to eight metres, lie the charcoal and burnt stone that are the characteristic signature of these ancient cooking sites.

A fulacht fia is essentially a prehistoric open-air cooking place, typically consisting of a trough dug into the ground, a hearth for heating stones, and a mound formed over centuries from the discarded burnt and shattered stone that accumulates after repeated use. Heated stones were dropped into a water-filled trough to bring it to the boil, and the cracked, spent stones were piled to one side. They are found in their thousands across Ireland, usually in low-lying, wet ground, and the Glenmagoo example fits that pattern closely. The site sits at the foot of a south-facing slope in what was formerly marshy ground, the kind of damp, sheltered location these sites consistently favour. The spread of burnt material was first identified and recorded in 1987, though the levelling of the mound itself had already taken place decades earlier.