This barrow belongs to a class of monument called Entrance Graves or Chambered Tombs, consisting of a circular kerb of stones with an entrance passage, the whole of which would originally have been covered by a mound of earth and stones. Other examples may be seen at Brane Barrow (near to Sancreed), Tregiffian Barrow (near to the Merry Maidens stone circle), and at Chapel Carn Brea and Ballowal Barrow near St.Just [all available as downloadable leaflets]. They date from the Neolithic period (approx. 3000-2500 BC). Bosiliack Barrow is 4.95m (16.5ft) in diameter with a probable original height of 1.5m (5ft). It was excavated in 1984, when a primary deposit in a pot was discovered, as well as topsoil and turf that might have been placed in the chamber as ritual deposits associated with the fertility of the land.