It is a Physalia physalis or else man-of-war. It is a marine animal of Physaliidae family living in the Atlantic, Indian and Pacific Ocean. The long tentacles make a painful sting, which is poisonous and powerful enough to kill fish or even (rare) people.

Despite its appearance, the Physalia physalis is not a jellyfish but sifonoforo, which is not really a multicellular organism. It is a colonial organism made up of individual animals of the same species called zooid or polyps. These polyps are interconnected and integrated, creating a symbiotic relationship and functioning as an individual animal.