A spooky Swedish island has revealed evidence of 9,000-year-old cave rituals to a team of archaeologists who are studying the isle's surprisingly active Mesolithic history, LiveScience reports. Blå Jungfrun, which lies off the east coast of Sweden, has been believed for countless centuries to be a site where witches gather every Easter to worship the devil; additional stories claim that taking a rock from the island curses the thief to a lifetime of bad luck.