Why are octopus, squid, cuttlefish, jellyfish called “live rockets”?

Behind the head of these species, the edge of the fleshy mantle protrudes, which forms a collar around the “neck”. At the edge of the mantle, on its inner surface, there are cartilaginous “umbrellas” that are capable of passing water. Funnels “nozzles” protrude from under the edge of the mantle. Water gets into the inside of the mantle, the cufflinks snap into place, and the muscles in the wall contract. Water from under the mantle finds a way out only through a funnel. Usually it is directed forward, and the animal is thrown back. Then everything is repeated.