What survives is a narrow megalithic chamber, roughly 2.3 metres long and less than a metre wide, oriented east to west and covered by a single roofstone propped at the western end by a large upright slab. Three stones form each of the long sides, and the eastern end is closed by a single orthostat, a term for one of the large standing slabs used as a structural element in prehistoric stone construction. The sides project slightly beyond that closing stone, a detail that hints at a more complex original design, though too much has been lost to say with confidence what the monument once looked like in full.

Because so little remains, archaeologists Ruaidhrí de Valera and Seán Ó Nualláin, who catalogued megalithic tombs across Ireland through the mid-twentieth century, were unable to assign the structure to any recognised tomb type when they recorded it in 1972. Portal tombs, court tombs, wedge tombs, passage tombs: each follows broadly distinct architectural conventions, and the surviving fabric here does not offer enough evidence to place it firmly within any of those categories. That ambiguity is itself a kind of information. It suggests either significant disturbance over the millennia, or perhaps a regional or transitional form that does not map neatly onto the established classifications. The name Labbadermot, from the Irish leaba, meaning bed or grave, is commonly attached to megalithic remains across Ireland and points to a long folk memory of the site as a place of burial, whatever its precise prehistoric origins.

The monument sits close to the seashore, and its incorporation into a field boundary fence means it exists now as part of the everyday agricultural infrastructure of the townland of Knockbrack. Visitors approaching the eastern side of Sellerna Bay should look carefully at field boundaries rather than expecting an obviously monument-like form rising from open ground.