Female argonaut at Cabrillo Marine Aquarium

On Saturday, October 13, 2012, a female argonaut (aka paper nautilus) was caught by fishermen when they were fishing for squid a couple of miles from Los Angeles Harbor. These animals are usually only found in tropical and subtropical seas; finding one in Southern California indicates warm water currents from the south are most likely prevalent.
Argonauts are a type of octopus. They eat plankton such as krill, shrimp and pelagic snails. Female and male argonauts reach dramatically different sizes; females grow to be about 18 inches and males only one inch! The female argonaut creates a thin, laterally compressed calcareous shell, which is secreted and formed by the first arm from a wide sail-like lobe. This shell has one chamber that is used as a brood pouch for eggs.

[@falcosparverius1]

search utube: Live Argonaut found in its shell the Paper Nautilus, it shows an Argonaut out of the shell with the 2 wide sail-like tentacles exposed...
ur video shows one of the special sail-like tentacles being deployed inside the shell..could now see why the shell is see through, so the sail-like lobe tentacles can change colors to camouflage the animal...the purple iridescent color shift...almost like the deep purple of the open seas...then silver to match bright sunlight. pretty cool : )

[@seiyuokamihimura5082]

falcosparverius1 argonauts don't have "shells" the "shell" is the female argonauts egg case.