These are among the most common prehistoric monuments in Ireland, yet they remain oddly understated features in the landscape, easy to overlook as a low horseshoe-shaped mound beside a marshy hollow. The typical fulacht fia consists of a trough, often timber-lined or stone-lined and dug into the ground, alongside a hearth and a mound of fire-cracked stone. Water was brought to the boil by heating stones in the fire and dropping them into the trough. The burnt and shattered stones, discarded after use, built up over time into the distinctive crescent mound that survives today.

Mooghaun itself is a place of considerable prehistoric weight. The hillfort nearby dates to the late Bronze Age and is notable both for its scale and for its association with the Mooghaun hoard, discovered in the nineteenth century, which comprised a large collection of gold objects and remains one of the most significant Bronze Age gold finds in northern Europe. Fulachtaí fia are generally dated to the Bronze Age, roughly 1500 to 500 BC, though some examples in Ireland fall outside that range. Their precise function has been debated for decades. Cooking is the most widely accepted explanation, with experimental archaeology demonstrating that water in a wooden trough can be brought to a full boil within minutes using the hot-stone method, and that a large joint of meat can be cooked efficiently by this means. Other theories have proposed use for textile processing, bathing, or brewing, and the reality may be that different sites served different purposes at different times.