The one at Toorard, in County Mayo, is a characteristic example of a site type that refuses to announce itself: typically a low, kidney-shaped or horseshoe mound of fire-cracked stone and dark, charred soil, sitting close to a water source and easy to walk past without a second glance. What makes burnt mounds collectively strange is not any dramatic appearance but the question they pose. Nobody is entirely certain what they were for.

Burnt mounds, known in Irish archaeology as fulachta fiadh, appear across Ireland and Britain mostly in the Bronze Age, roughly between 1500 and 500 BC, though some date earlier or later. The standard interpretation is that they functioned as cooking sites: stones were heated in a fire, dropped into a water-filled trough to bring it to the boil, and the cracked, spent stones were then discarded in the spreading mound that still survives. Experiments have shown that a decent-sized animal carcass can be cooked this way in a few hours. Competing theories have proposed uses ranging from textile dyeing and hide preparation to communal bathing, and some archaeologists suspect these sites served different purposes at different times and places. The mound at Toorard sits in a part of Mayo where such monuments are not uncommon, a county whose boggy, low-lying ground has preserved prehistoric features that drier soils elsewhere would long since have erased.