It measures nearly fourteen metres long, over twenty-one metres wide, and rises to about one and a half metres at its highest point, with an opening of just over two metres facing west. What it represents is far older and stranger than its modest appearance suggests: this is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically dating from the Bronze Age. The characteristic mound is composed of burnt and shattered stone, the discarded debris of a process that involved heating rocks in a fire and dropping them into a water-filled trough to bring the water to a boil.

Fulachtaí fia (the plural form) are among the most common archaeological monuments in Ireland, yet their very ordinariness makes individual examples easy to overlook. The horseshoe or kidney shape is typical of the type: the trough, usually of wood or stone, would have sat in the hollow at the centre, and the crescent of scorched, cracked stone built up around it over repeated use. The precise purposes served by these sites have been debated at length; cooking is the most widely accepted explanation, but brewing, hide-working, and bathing have all been proposed. The example at Rowls has its opening oriented to the west, and its position close to the River Allow is entirely consistent with the pattern seen at sites elsewhere, where proximity to a reliable water source was clearly a practical necessity.