Nautilus Pompilius - yes, yes, the same one.

But this cephalopod can, by adjusting the amount of ammonia ions in the chambers of the shell, sink or float - the principle that is used in modern submarines was invented by him hundreds of millions of years ago.

Most modern cephalopods lack a shell and have an elongated body with a small number of head tentacles. At the same time, in the Paleozoic, hundreds of millions of years ago, ammonites and nautiloids flourished, possessing a well-developed outer shell and numerous tentacles.

The ammonites that dominated past geological eras have completely died out, but a small number of nautiloid species have managed to survive and survive in the tropical regions of the Pacific and Indian oceans. For this reason, the nautilus, along with the coelacanth, horseshoe crabs, and some other species, are called "living fossils."

Ancient nautiluses grew up to 3.5m, but the current ones only up to 25 cm - but thanks for that, but they survived!
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