The term refers to burnt mounds, typically crescent or kidney-shaped accumulations of fire-cracked stone and charcoal-rich soil, thought to be the residue of some kind of communal cooking or heating activity, probably involving a water-filled trough heated by dropping fire-heated stones into it. The example at Caherweelder in Co. Galway is a particularly well-preserved instance of this type, sitting in a low-lying marshy area on the western fringes of a turlough, which is a seasonal limestone lake that floods and drains according to groundwater levels rather than rainfall directly.

The mound was first formally inspected in December 1982, when it presented as a kidney-shaped form measuring roughly 11.8 metres north to south and 8.1 metres east to west, rising about 0.8 metres above the surrounding ground. Burnt stone and clay were visible where the grass cover had been broken. It might have remained a quiet footnote in the broader record of such monuments had the route of the N18 Oranmore to Gort motorway not passed directly through it. That necessity prompted a full excavation in 2008, which revealed the mound to be even more substantial than the 1982 measurements suggested, reaching 14 metres north to south, 10 metres east to west, and a maximum height of 1.1 metres. Excavators working by hand across roughly 200 square metres uncovered what may be the original cooking trough, a cut measuring approximately 2.15 metres by 1.3 metres located 1.5 metres from the centre of the mound and partially beneath its north-east quadrant. Immediately north of it lay a possible upcast mound, the spoil heap left when the trough was first dug, measuring around 2 metres by 0.95 metres. Together, these features describe the working anatomy of a prehistoric site that was almost certainly chosen for its proximity to standing water.