Octopod

An Octopod was an organic construct that served as a weapon of the Rutan Host.

In 1918, one such creature had its ship crash on the planet Earth where it lay in the waters of the Bermuda Triangle. In that time, it attacked the USS Cyclops where it was believed by the human crew to be a giant squid. At the time, the Tenth Doctor and Heather McCrimmon had used the TARDIS to travel to there. They discovered the true reason why the Cyclops had sunk. They halted it temporarily by throwing manganese ore from the cargo bay on it. This disrupted the Octopod's magnetic field, forcing it back into the sea.

The distraction allowed them to escape. The Doctor revealed he could not save the ship as it was part of history. Its destruction would remain a mystery to mankind. (DWA: Cyclops)


 * The fate of the creature remains unknown. It's possible it still exists beneath the oceans on the planet, continuing its directive.