Blanket Octopus are 4 species of the genus Tremoctopus. They are found throughout the world's tropical and sub-tropical oceans, from the surface to moderate depths. I usually think of octopods crawling around on rocks and such but the Blanket Octopus is pelagic, living life out in the open ocean with no need for coasts or the sea floor at all.
And of course, "living life" is one of her top priorities, so she requires some kind of defence against whatever predators she may come across. She has no octopus ink, so this is when her Giant Security Blanket of Doom makes its dramatic appearance.
A female Blanket Octopus might get to about a meter or 2 (3.3 to 6.6 feet) in length, but her first 2 pairs of legs are extra specially long. Attached to them is a huge span of webbing that is normally hidden away. In times of need, this drapery is unfurled, spread out and left to billow in the water. It's like curtains on a dark and stormy night, when you really ought to close those windows. This makes her look far larger and more threatening than she actually is, hopefully scaring off any predators. If it doesn't seem to be working so well, bits of her blanket can even detach from the rest to act as a decoy. Quite the bag of tricks!