The site at Formoyle is the most substantial of the three, a horseshoe-shaped mound of fire-cracked stone measuring about ten metres north to south and nearly twelve metres east to west, rising to a maximum height of one and a half metres. At its open end, facing north-northwest, lies the remains of a shallow trough, roughly three metres by one metre, where water would once have been heated by dropping in stones that had been made scorching hot in a fire nearby.

A fulacht fia, the term used for these Bronze Age cooking monuments, is essentially the accumulated debris of that repeated process: stones crack and shatter when heated and then plunged into water, and over time the discarded fragments build up into the distinctive mound that survives today. They are among the most common prehistoric monuments in Ireland, yet the concentration here is notable. The Formoyle site was first identified by Michael Mahon in 1991, and two further examples lie within easy walking distance to the south-southeast and south-southwest. The location itself carries an added layer of oddness: the stretch of valley known locally as the Khyber Pass, a name borrowed from the famous mountain corridor on the Afghan-Pakistani border, presumably on account of its own narrow, hemmed-in character. That a Bronze Age cooking site overlooking a Clare river should share its address with a Central Asian mountain range is one of those small geographical jokes that the Irish landscape occasionally produces.