The alignment runs north to south for about eight metres, barely noticeable unless you are already looking for it, and it represents what may be the remnants of a fish weir, a structure built to trap fish as the tide retreats by funnelling them through a fixed barrier of stakes and netting or woven branches.

The feature was recorded in July 1994 and is described by Aidan O'Sullivan, writing in 2001, as a post alignment of possibly post-medieval date, meaning it could belong broadly to the period from the sixteenth century onwards, though the qualification reflects genuine uncertainty about its age. Post alignments of this kind are found at a number of points along the Shannon and other Irish estuaries, and fish weirs of various forms had been in use along Irish coasts and rivers for centuries before that period. The estuarine clays in which these posts are set can preserve organic material unusually well, which is part of what makes low-water features like this one worth recording at all.