Kraken

Appearance
The Kraken is a legendary sea monster that resembles a large squid or octopus, however, it only has 7 appendages instead of 8. It is said to live in the coasts of Norway and Greenland.

History
In the late 13-century version of the Old Icelandic saga, Örvar-Odd is an episode of the protagonist's journey to Helluland (Baffin Island). During their trip through the Greenland Sea, they spot two gigantic sea monsters, the Lyngbakr and the Hafgufa (The Kraken). After returning from Greenland, the author describes the monster's physical traits and feeding behavior. They also mentioned that there were only two in existence because they have always been spotted around the same location in the Greenland Sea, and that it seemed that both were incapable of reproduction.

Later on, Erik Pontoppidan mentions this monster in his work Det første Forsøg paa Norges naturlige Historie "The First Attempt at Natural History of Norway". He tells us that the creature is so big that sometimes it can be mistaken for an island. He also tells us that the real dangers to sailors was not the creature, but the whirlpool left in its wake. Pontoppidan then describes the violent capabilities of this creature: "it is said that if it were to lay hold of the largest man-of-war, it would pull it down to the bottom." The fishermen decided to take this risk and fish over Kraken because the catch was so plentiful (thus the saying "you must have fished on Kraken"). Erik also claims that a specimen of Kraken washed up on shore and died at Alstahaug in 1680.

In 1802, French malacologist Pierre Dénys de Montfort discovered the existence of two species of giant octopus. One being the Kraken Octopus, which was the one described by Norwegian and American sailors. The other being the Colossal Octopus, depicted as being much larger than the Kraken and was reported to have attacked a sailing vessel from Saint-Malo.

Possible Explanations
People believe that the Kraken may have been based off of the giant squid.