June 29, Beijing Time -- According to foreign media reports, crop circles refer to strange patterns that appear overnight in wheat, rye, barley and similar crops. These patterns are complex, including geometric shapes and circles, as well as abstract concept shapes. They are usually formed when the stalks grow to a certain height off the ground and then fall in the same direction. Some crop circles can be explained, while others remain a mystery to this day. Crop circles that cannot be proven to be human-made often exhibit strange characteristics that are difficult or impossible to replicate. Blame on aliens?