Easy to dismiss as debris, it is in fact the remains of a fish weir, a post-medieval structure used to trap fish on the tidal ebb. Fish weirs of this type worked by driving stakes into the riverbed or estuary floor, often strung with wicker or netting, so that fish moving with the tide would be funnelled and caught as the water receded.

The weir sits adjacent to Bunratty West townland, to the west of Quay Island. Archaeologist Aidan O'Sullivan, who recorded it in February 1997, described it as a post alignment oriented east to west and running some four to five metres in length within a narrow creek in the modern mudflat. That modest scale does not diminish its interest. Post-medieval fish weirs are relatively underdocumented compared to their medieval counterparts, and the survival of even a partial alignment in the intertidal zone is notable. The Shannon estuary was intensively fished for centuries, and structures like this one represent the practical, unmonumental side of that history, the kind that rarely makes it into the written record.