It is a fulacht fia, one of thousands of Bronze Age cooking sites scattered across Ireland, and its ordinariness is precisely what makes it interesting. These sites, found in their thousands from Cork to Donegal, typically consist of a horseshoe-shaped mound of heat-shattered stone beside a trough, into which water was poured and heated by dropping fire-cracked rocks directly into it. The process sounds rudimentary, but experiments have shown it works efficiently, bringing water to a boil within minutes. That so many of these sites survive, even as grass-covered humps most walkers would step over without a second thought, is one of the quieter curiosities of the Irish countryside.

The fulacht fia as a monument type dates broadly to the Bronze Age, roughly 1500 to 500 BC, though some examples have produced earlier or later dates through radiocarbon analysis. The name itself is medieval Irish, sometimes translated as "cooking place of the Fianna", linking the sites in folk memory to the roving warrior bands of Irish mythology, though the actual users were almost certainly more prosaic, ordinary communities going about the business of preparing food, and possibly processing hides or even bathing. Lydacan is a small townland in east Galway, and the presence of a fulacht fia there fits a broader pattern; low-lying, water-adjacent ground in the west of Ireland is particularly dense with these monuments, often clustering near streams or boggy hollows that would have provided the necessary water supply.