Crop formation in the form of the "Mandelbrot Set" at Ickleton, near Cambridge, England. The formation appeared in August 1991. Crop formations are patterns of flattened plants in crops such as wheat or barley. They started appearing frequently in the mid-1980s in south-west England. Their cause is unknown. Many theories exist, ranging from science-based physical explanations such as the "plasma vortex" theory based on the phenomenon of electrohydrodynamics (EHD) to unorthodox suggestions that they are created by extraterrestrial intelligences. The Mandlebrot Set results from a mathematical method of repeated 'chaotic' subdivision, a form of fractal geometry. Heart-shaped with circles.