Called the Lion’s Mane Jellyfish, the biggest jellyfish that was ever found was 2.3 meters (7 feet 6 inches) wide, and 37 meters (121.4 feet) long. The length was due to the innumerable tentacles. It was found washed ashore in Massachusetts Bay in 1870. Also known as the giant jellyfish or the hair jelly, various specimens have been of different colors ranging from orange to purple. Like most jellyfishes, the giant jellyfish also glows in the dark.