They are the remnants of a fish weir, a structure that in its working life would have guided fish into a trap or enclosure as the tide ebbed. Weirs of this kind were once common along Irish estuaries and tidal creeks, but most have left no trace above ground. These posts have survived, quietly waiting out the centuries in the anaerobic silt.

The structure was recorded in July 2000 by Aidan O'Sullivan, whose survey of the Shannon estuary's intertidal archaeology catalogued a remarkable range of such remains. He described the feature as post-medieval in date, oriented NNE-SSW, and situated on the north bank of a creek on the upper foreshore, northwest of Bush Island. The double-row alignment is characteristic of a particular style of tidal fish trap: stakes driven into the riverbed or foreshore in converging or parallel lines, sometimes threaded with wattle or netting, funnelling fish towards a catching point. The post-medieval period, broadly spanning the sixteenth to eighteenth centuries, was a time when Shannon estuary communities depended heavily on fish as both a food source and a tradeable commodity, and such weirs were working infrastructure rather than curiosities.