These low, elongated stone troughs, typically set into the ground or built at ground level from dry-stone walling, were used to burn harvested seaweed at intense heat, reducing it to a calcium-rich ash that was sold for use in the production of glass and soap, and later iodine. The trade was not incidental to life here; for many island and coastal communities along the western seaboard, kelp burning was a primary source of cash income across the eighteenth and nineteenth centuries.

Kelp harvesting on the Aran Islands followed a seasonal rhythm shaped by tidal patterns and the availability of labour. Families would gather seaweed from the shore, spread it out to dry, and then burn it in kilns over a slow, carefully managed fire that could take days to complete. The resulting block of solidified ash, called a kelp cake, was weighed and sold to merchants who traded it onward to industrial processors. The industry peaked in the eighteenth century, when duties on imported barilla, a plant ash used for the same purposes, made Irish kelp economically competitive. It collapsed sharply in the early nineteenth century after changes in duties and the development of cheaper chemical alternatives. The kiln at Eoghanacht is a physical remnant of that period, sitting in a landscape that still carries the field systems, stone walls, and limestone pavements shaped in part by the labour of that era.