The adjustable, discoid rotary quern has larger, flatter and more discoid stones than the beehive type. The lower stone was completely perforated. The long handle rotated in a shallow socket in the upper surface of the upper stone. They are thought to have originated in Spain 2,500 years ago and appear to have arrived in maritime Scotland from about 200 BC with people who built the defensive homes known as brochs. This Iron Age type closely resembles the adjustable Highland quern still in use in historic times.