Video courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (mp4, 11.4 MB).
Tangled mass of string floating along in the ocean?
Nope. It's a siphonophore!
And if the fact that it is alive isn't weird enough, consider this: It's not one individual animal, but a whole bunch working together as a single colony. Talk about teamwork!
Seen exploring at a depth of approximately 800 meters (2,625 feet) off of Hawaii during the Deep-Sea Symphony: Exploring the Musicians Seamounts expedition.