It was first reported by a local researcher named Ciarán Rock, and for all practical purposes it remained unrecorded before that point, swallowed by a mature coniferous forest that has done a thorough job of keeping it out of sight.

What survives is the heavily damaged remains of a court tomb, a type of megalithic burial monument built in Ireland roughly five to six thousand years ago and characterised by a roofed stone gallery set within a long cairn, with a semicircular or U-shaped forecourt at one end where ritual activity is thought to have taken place. At Tullyskeherny, the cairn, oriented broadly east-north-east to west-south-west, measures around fifteen metres in length and eight metres in width, though it has been truncated on all sides and stands only about a metre high. Within it, a fragment of the original gallery is still legible: five metres or more of walling defined by two large orthostats on the north side and three on the south, though the western end disappears beneath accumulated cairn material. At the eastern end, two upright jamb-stones, set just half a metre apart, would once have marked the threshold between the forecourt and the burial chamber. A single court stone survives immediately to the north of this entrance, and two further possible court stones stand nearby, one of them roughly four and a half metres to the east of the jambs. No roof-stones were identified during the survey, which means the chamber, if ever covered, has lost its capstones entirely.

The shelf of relatively level ground on which the tomb sits would have made it a reasonable choice for a construction project of this scale, even if the forested hillside now makes the setting feel deeply enclosed. The trees arrived long after the people who built it, and the monument predates any map that might have recorded it.