These sites, sometimes called burnt mounds, are the remnants of ancient outdoor cooking or processing places, typically consisting of a mound of fire-cracked stones, a hearth, and a trough, often timber-lined, in which water was heated by dropping in stones heated in a fire. They cluster near water sources, and thousands have been identified across Ireland, with the majority dating to the Bronze Age.

What makes the Knockavullig site particularly interesting is its proximity to a second fulacht fia, recorded roughly fifteen metres to the south-west. Whether the two were in use simultaneously or represent activity at different periods, their closeness suggests this particular stretch of ground beside the stream was returned to repeatedly. The burnt material noted here is characteristic of the type: fire-cracked stone discarded after use accumulates over time into a low, horseshoe-shaped mound, dark and scorched against the surrounding soil.