Iron plough coulter
Roman Britain, 1st-4th century AD
From Great Witcombe, Gloucestershire
The coulter was a technical innovation introduced to Britain by the Romans. Its function was to make a vertical cut in advance of the plough-share, which then undercut the furrow made by the coulter. This made it easier to cultivate heavy soils. Roman coulters were therefore stout knife-like iron blades with a heavy shaft by which they were secured to the plough's wooden beam.
W.H. Manning, Catalogue of the Romano-Britis (London, The British Museum Press, 1985)