For centuries they've puzzled people by their curious appearance. They crop up in fields across the globe, in patterns ranging from the simple circle to the DNA double helix. Right now in America...it's crop circle season. This year they're popping up all over the Midwest, with recent sightings in Geneseo, Ill.; Sandyville, Ohio; and Huntingburg, Ind. And the list goes on. What exactly are they?" said Stan Friedman, a nuclear physicist and author of the book Crash at Corona: The Definitive Study of the Roswell Incident. "The fact that people can fake [crop circles] doesn't mean that there aren't real ones. I have no qualms about the possibility that aliens are appearing," Friedman said. Many experts are unprepared to rule out aliens. As the Gallup Polls tell, three-fourths of people in this country believe in paranormal activity. Colin Andrews, a world-leading crop circle expert [has] done extensive research that [he says] proves that not all crop circles come from humans. Andrews and his team conducted a study in central-southern England during 1999-2000, which assessed more than 200 circles. That study showed around 80 percent of crop circles to be man-made with the remaining number unaccounted for. According to Andrews, crop circles not made by humans exhibit a number of peculiar traits. He says that the soil from these circles has a higher magnetic reading and that the position of the circle in the field will relate to the color or nutritional value of the individual plants.