To the untrained eye it looks like little more than a slight darkening of the ground, but it is the remains of a fulacht fia, one of the most numerous and least-understood monument types in the Irish landscape. These are the scorched debris mounds left behind by a prehistoric cooking method: stones were heated in a fire and dropped into a water-filled trough, bringing it rapidly to a boil, and the cracked, fire-reddened fragments were then raked aside into a mound. Over centuries, sometimes millennia, grass grew over the discarded material, preserving it as a low, often horseshoe-shaped spread.

What makes Knockearagh quietly notable is not just the monument itself but the fact that a second fulacht fia lies roughly 120 metres to the south-east. Their proximity to one another, and both sites' close relationship to the nearby stream, reflects a pattern seen repeatedly across Ireland: these sites cluster near reliable water sources, which were essential to the whole process. Whether the two sites were used at the same time, by the same community, or represent activity separated by generations is unknown, but the pairing is a reminder that what looks like an isolated curiosity in a modern field was once part of a worked and inhabited landscape.