noun - Comb jellyfish or comb jellies live in oceans around the world. Their most distinctive feature is the "combs", groups of cilia they use for swimming. They range in size from a few millimeters to 1.5 meters. its fossils have been found as far back as about 525 million years ago.
Their bodies consist of a mass of jelly, with one layer of cells on the outside and another lining the internal cavity.