https://en.m.wikipedia.org/wiki/Siphonophorae
Siphonophores belong to the Cnidaria, a group of animals that includes the corals, hydroids, and true jellyfish. There are about 175 described species. Some siphonophores are the longest animals in the world, and specimens as long as 40 meters have been found. The majority of siphonophores are long and thin, consisting mostly of a clear gelatinous material.
http://www.siphonophores.org/index.php
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