It measures roughly eighteen metres from north to south and ten metres across, rising only half a metre from the surrounding marsh, and it has two openings facing west. Unspectacular to look at, it is in fact a fulacht fia, one of the most common yet persistently mysterious monument types in the Irish landscape. The term, sometimes translated loosely as "cooking place of the deer," refers to a type of prehistoric site where stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil. The spent, shattered stones were piled to the sides over repeated use, forming the characteristic horseshoe-shaped mound that survives today.

Thousands of these sites have been recorded across Ireland, most dating to the Bronze Age, roughly 1500 to 500 BC, though some are earlier or later. Their precise function has been debated for decades. Cooking meat is the most widely accepted explanation, and experimental archaeology has shown the method works efficiently, but researchers have also proposed uses ranging from textile processing and leather-working to bathing and brewing. The location beside water is not accidental; a reliable supply was essential to the whole process, and marshy or low-lying ground beside streams is exactly where fulachta fiadh are routinely found. The Liscarroll example fits the pattern closely, its placement between two watercourses suggesting the site was chosen with the same practical logic that guided Bronze Age communities across the country.