The one recorded at Monaincha in County Tipperary has the particular distinction of being a place that has, in effect, ceased to exist. When surveyors visited the site, they could not locate it at all.

On the first edition Ordnance Survey six-inch map, published in 1843, the crannog appears clearly as an island set within a small lake in the surrounding bog. By the time the second edition was produced in 1904, it had already vanished from the cartographic record. The intervening decades tell much of the story. The bog passed into private ownership and was progressively cut for turf. As the peat was stripped back to mineral soil across most of the area, no preserved layers of ancient wood were uncovered, which might otherwise have confirmed the structure's original extent or composition. Drainage channels were cut through the bog surface at irregular intervals, and by the time of any modern investigation, the landscape had dried out sufficiently for natural scrub woodland to begin establishing itself on the surface. The lake that once surrounded the island had disappeared along with the wetland conditions that created it.