When it was first recorded in 1991, the feature measured roughly seven metres by three, defined by a shallow ditch about a metre wide with faint traces of an outer bank. That combination of ditch and bank is the kind of thing that archaeologists associate with a barrow, a burial mound of prehistoric origin, and that is indeed how it was initially classified.

The problem is that the feature does not quite fit. Barrows tend toward the circular, and the rectangular footprint here closely resembles a kelp-drying kiln, a structure type found at several other points along the west Sligo coast. These kilns were used in the post-medieval and early modern periods to process harvested seaweed, burning it down to produce an ash rich in alkali that was sold to the glass and soap industries. The form, the size, and the coastal position at Lackan all point at least as plausibly in that direction as toward any prehistoric burial. It is a reminder that the landscape of the Irish west coast layers different kinds of labour and different periods of history on top of one another, and that what looks ancient is not always what it seems. A second possible barrow lies about 150 metres to the north-north-east, which might, depending on how the first feature is eventually interpreted, either strengthen or further complicate the picture.

That picture may never be resolved. By the time anyone went back to look more carefully, in 2013, land reclamation had removed every visible trace of the monument. There is nothing left to see at the site today, and the question of whether it was a burial place or a place of industrial work has been quietly swallowed by the pasture.