No, that’s not an alien that’s sweeping through the void to end your life and consciousness with a single, silent whip of its stringy tentacles. It’s a squid.
Which is maybe more terrifying, because it’s real.
Magnapinna squids are one of the deep-sea more ethereal creatures. Little is known of these squid as very few have ever been captured … They are unusual in both that the fins are up to 90% of the length of the body, i.e. the mantle, and the ridiculously long length of the arms. The squid often will hold some of the arms at a 90˚ angles from the side of the body.
The image above comes from this old video, and what with the jerky camera work, it does feel a little bit like a bad horror movie. Just another reason we should save the oceans: so these things NEVER have an excuse to come take their revenge.