Crop circles are patterns formed by flattened crops, usually cereal grains, that have historically been observed in fields in southern England and other regions. While some are hoaxes, many remain unexplained. Witnesses have reported sightings of lights and anomalous phenomena in fields where complex crop circles later appear. Scientific analysis has found that crops in circles are bent in a way that differs from being manually flattened. The origins and formation of many crop circles remain mysterious.