There is a creature named Kraken in Scandinavian and Finnish mythology. It is a type of squid or huge octopus that supposedly emerges from the sea and attacks ships and devours crew members.
There are legends in which it has been represented as a species of crustacean similar to a lobster.
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This octopus and it's habit of attacking ships and crew members make me never want to go on a ship ever due to to fear of being devoured by the octopus.
There's many mysteries hidden in the seas.