Today I Learned: Portuguese man-of-war

From a novel I'm reading now called The Ten Thousand Things by Maria Dermout:

"'Holothuriae, the 'mizzen': they have many names, small galleon, Portuguese man-of-war, sea cucumber'--they have little sails, wide at the bottom, small at the top--listen to this! 'The mizzen can lower or raise this little sail when it feels the wind and wants to sail. Under water a mass of streamers, four or five feet long, hang down from it; the color is a beautiful blue, through which however something green plays. The body is transparent, as if a crystal bottle had been filled with blue-green aqua fortis.
"'The sails are milk-white with an upper edge of purple or violet, beautiful to behold, as if the creature were a precious jewel.'
"And this: 'it is miraculous to see a whole fleet of them, a thousand little ships--all together!'"

I looked online for this creature and of all its names referenced above, the only one that fit the description was the Portuguese man-of-war:



I think it rather looks like a human brain! Here is what that website says about this creature (I wonder if this information was known at the time (1955) the above novel was written):

The Man-of-War (also known as a bluebottle) is not one creature, as it is commonly assumed, but a complete colony of numerous polyps...each performing their own functions. There are polyps which do nothing but digest the captured food and distribute nutrients to polyps which are not capable of digestion on their own. There are polyps which produce the Medusa, a disc shaped organism which produces eggs and sperm. This organism breaks away from the main Portuguese Man-of-War and floats off to produce many more polyps which, in turn, gather together to form another complete creature. There could be hundreds of polyps which make up the creature we know as the Portuguese Man-of-War.

So the Portuguese man-of-war is large, it contains multitudes. Also, those streamers are poisonous so avoid.