Jellyfish or jellies are the major non-polyp form of individuals of the phylum Cnidaria. They are typified as free-swimming marine animals consisting of a gelatinous umbrella-shaped bell and trailing tentacles. The bell-shaped jellies - distantly related to corals and anemones - launched their lifestyle long, long ago. Exquisite jellyfish fossils found recently in Utah display reproductive organs, muscle structure and intact tentacles; the jelly fossils, the oldest discovered, date back more than 500 million years, when Utah was a shallow sea. By contrast, fish evolved only about 370 million years ago.