It is a cist, a type of prehistoric burial box built from upright slabs, and what makes this one worth attention is not its size but its geometry. Subcircular rather than the more common rectangular form, it measures just 1.25 metres north to south and 0.9 metres east to west, yet its builders arranged ten principal upright stones with a care that is still legible today.

The monument was exposed and largely cleared of peat around 1970, revealing the stones as they had been set directly into the pre-bog soil. Each upright has its long axis aligned with the perimeter of the chamber, giving the whole structure a coherent rotational logic. A further stone sits externally at the south-east corner. Most striking is the deliberate east-west axis running through the arrangement: three larger, taller stones cluster at both the north-west and south-east corners, creating a kind of emphasis at either end of that line. Two internal stones at the north-east sit slightly awkwardly within the overall pattern, though they appear tightly enough fitted to be structural rather than intrusive. Whether this reflects a repair, a later adjustment, or simply the practical problem of fitting irregular stones into a curved wall is not recorded.