The spring has long since been drained, but the horseshoe-shaped mound beside it is evidence of activity that happened here repeatedly, over centuries, during the Bronze Age. This is a fulacht fia, a type of site found in enormous numbers across Ireland, and one of the most debated categories of monument in Irish archaeology.

A fulacht fia typically consists of a mound of fire-cracked stone and charcoal built up around a trough, usually timber-lined or cut into the ground, into which water was channelled and then heated by dropping in stones that had been made red-hot in a nearby fire. The precise purpose of these sites has been argued over at length; cooking is the most widely accepted explanation, though brewing, hide-processing, and bathing have all been proposed. What makes the Curraduff example quietly interesting is its setting and its dimensions. The mound measures roughly 8.5 metres north to south and 15 metres east to west, and rises only about a quarter of a metre above the surrounding pasture. Its opening, some 3.2 metres wide, faces east, towards where the spring would once have provided a ready water source. That relationship between monument and water source is entirely characteristic of the type, and the draining of the spring does nothing to obscure it for anyone who knows what to look for. A second fulacht fia lies roughly 120 metres to the north-west, which suggests this particular corner of Curraduff saw sustained, repeated use rather than a single episode of activity.