They appear as low, horseshoe-shaped mounds, typically dark with organic matter, and are found near water, which gives a strong clue to their purpose. The prevailing interpretation is that they were ancient cooking sites, in use roughly between 1500 and 500 BC during the Bronze Age, where stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil. The mound itself is the accumulated debris of those fire-cracked stones, discarded after repeated heating and cooling had left them too fractured to be useful again. One such site sits in the townland of Callow in County Mayo, a quiet reminder that this corner of the west was once a place of regular, purposeful human activity.

The townland name Callow derives from the Irish "caladh", meaning a riverside meadow or low-lying wetland, the precise kind of terrain where fulachtaí fia tend to cluster. Mayo as a county has a significant concentration of these monuments, which is partly a reflection of the boggy, wet ground that both preserved them and, in prehistory, supplied the reliable water source their function required. Beyond its location in this particular townland, detailed records for this individual site remain limited in what is publicly available at present, meaning its precise dimensions, condition, and any finds associated with it are not yet fully documented in accessible form.