The 'Portuguese man o' war' isn't one animal — it's a colony of thousands

What looks like a single jellyfish-like creature is actually a siphonophore: a colony of specialised, genetically identical zooids, one type forming the gas-filled float, others handling stinging, digestion and reproduction. None of the individual zooids could survive alone; together they function as a single organism.

— NOAA Ocean Service, Portuguese Man of War (Physalia physalis)