Crop circles

I hesitated to include crop circles on this list because I'm almost certain they could all be human-made. While many groups of people now claim to have developed and created the occasional—often beautiful—crop formations, there remains a segment of the population who believe that some crop circles are the result of unexplained phenomena.

Crop circles are found in almost every country. According to Crop Circle Central, the only countries where crop circles have never been reported are China and South Africa. Crop circles, as we know them, began appearing in the 1970s. However, in the 1990s, more intriguing, complex pictographs emerged. Believers suggested they might be a form of communication from extraterrestrials—or even from Earth itself. Those who said they were not human-made pointed to isolated oddities around the reflected circles: arranged ears of grain, cellular changes in the grain, and strange phenomena experienced by researchers viewing the circles, such as unexplained equipment malfunctions, sounds, and other physical effects.