What gives it away, or rather gave it away when it was recorded in 1989, was a faint circular rise in the earth, roughly ten metres across, with a scatter of burnt stone sitting on its surface. No visible trace survives today.

The site belongs to a category of monument known as a fulacht fia, a type found in enormous numbers across Ireland. The basic principle involves a trough, usually cut into the ground and sometimes timber-lined, filled with water and heated by dropping fire-cracked stones into it. The burnt and shattered stones that result are the most durable part of the whole arrangement, and they tend to accumulate into a characteristic horseshoe-shaped mound around the trough. Most fulachtaí fia date to the Bronze Age, though some are earlier or later. The Brusk example was identified by Cody in 1989 as a "largely levelled" specimen, meaning the mound had been reduced over time, probably by centuries of agricultural activity in what is already soft, low ground. The burnt stone scatter was the last legible sign of what had once been there. A second fulacht fia lies roughly 135 metres to the north-north-west, which suggests this corner of Galway was a place people returned to, or at least that the conditions here, water close to the surface, soft ground easy to cut, suited this kind of activity well.