It is a fulacht fia, one of thousands of such sites scattered across Ireland, and among the most abundant yet least celebrated monument types in the country. The name, loosely translated from Irish, refers to a burnt mound, and that is precisely what it is: the accumulated debris of repeated episodes of heating stones in fire and plunging them into water-filled troughs, most likely during the Bronze Age.

The fulacht fia was a practical technology. Stones were heated in an open fire until they were hot enough to raise the temperature of a wooden or clay-lined trough of water, and the cracked, spent stones were then discarded to the side, building up over time into the characteristic horseshoe-shaped mound that archaeologists still find today. What exactly these sites were used for remains a matter of some debate. Cooking is the long-standing explanation, and experiments have shown it works well enough for boiling large joints of meat. But brewing, textile processing, and bathing have all been proposed as alternative or additional functions, and the answer may simply be that different communities used the same basic method for different ends. The site at Leo has not yet been the subject of detailed published investigation, and the specific details of its size, condition, and context remain unrecorded in accessible form.