The one at Derryhick in County Mayo is a quiet example of a monument type that appears almost everywhere in Ireland yet continues to resist easy explanation. A fulacht fia typically survives as a low, horseshoe-shaped mound of fire-cracked stone and charcoal-blackened soil, curving around the site of a trough that was once dug into the ground nearby. The prevailing theory holds that these were cooking sites, used during the Bronze Age by heating stones in a fire and dropping them into a water-filled trough to bring it to a boil. Some researchers have proposed alternative uses, including textile processing or bathing, though the cooking interpretation remains the most widely accepted.

Bronze Age communities, active in Ireland roughly between 2000 and 500 BC, left fulachtaí fia in boggy, low-lying ground near streams and springs, where water would naturally collect in the trough. The characteristic mound of shattered stone built up over repeated use, each heating and sudden cooling causing the rocks to crack and eventually become unusable, at which point they were discarded to the side. Derryhick, a townland in Mayo, sits within a county that has produced numerous examples of this monument type, often preserved beneath peat where waterlogged conditions have kept organic material intact for millennia. The precise details of this particular site, its dimensions, condition, and exact setting within the townland, are not currently available in published form.