Siphonophores (Eschscholtz, 1829) belong to the phylum Cnidarians and are a class of marine invertebrates. They form super colonies which sometimes can resemble jellyfish. Although it might seem like one organism the colonies are formed by many distinct looking organism individuals. Some of the most famous members of this group are the Portuguese Man o' War (Physalia physalis) and Praya dubia, one of the largest animals in the world (40-50 m).
There are about 175 described living species of Siphonophores.
We have come across this organism a number of times, but, are still not certain if it really is a Siphonophore. But that is our best guess. Nevertheless did it fascinate us with its ability to completely disappear when put in water.