It is the kind of structure that leaves almost no trace above ground, surviving only because waterlogged conditions can preserve organic material for centuries.

The trap was a V-shaped fishtrap of the sort that worked by funnelling fish along two converging fence arms into a narrow basket from which there was no exit. The fence itself ran roughly north to south and varied between ten and twenty-two metres in length, built from rows of vertical posts reinforced with laid brushwood, post-and-wattle panels, the wattle being thin branches woven between upright stakes, and oblique braces to hold the structure against the pull of the tide. At the narrow end sat the basket: 4.1 metres long, 88 centimetres wide at its mouth and tapering to just 35 centimetres at the closed end. When archaeologist Aidan O'Sullivan excavated the site in February 1997 and revisited it in March 1999, a hazel rod from the structure was radiocarbon dated to 820 plus or minus 35 before present, placing its construction somewhere between AD 1164 and 1279. That range puts it firmly in the medieval period, when the Shannon was one of the most intensively fished waterways in Ireland and such traps were a practical, low-cost means of harvesting the river's resources without boats or nets.

The site location is noted as estimated rather than fixed with precision, which is a reminder that intertidal archaeology is a shifting business; what is visible during one low tide may be buried or dispersed by the next. Anyone curious about the estuary's medieval past is more likely to encounter the idea of the trap than the trap itself.