The pyrosome is so rare that for most underwater divers it may as well be a unicorn. It has only been caught on film a few times.
This one, seen drifting through the water in the video below, was found by Michael Baron of Eagle hawk Dive off the coast of off the Tasman Peninsula in Tasmania, in 2011.
The long tube in the picture is one pyrosome, but is actually made of dozens of animals that reproduce by cloning, then weaving their tissues together to form one long tube.
Pyrosomes start out as tiny transparent filter feeders that move through the water like an really slow-moving underwater jet ski. Pyrosomes are shaped like hollow tubes that are closed at the rear end. They suck water loaded with plankton through their open end and it passes through the body.
Tiny nodes line the inside walls of the tube, filtering our the plankton they use as food. You can see one bubbling in the video below. Then the animals squirt the water out behind them, the jets of water propelling them through the ocean.
They are even bioluminescent — they can flash a blue-green light can can be seen from several meters. And yes, they are as fluffy and delicate as they look.
The few divers who have actually touched them say they are as soft as a feather boa. Not that you should touch them, of course. You could either disturb them or discover you are actually touching the long tail of a venomous jellyfish.
In the second half of the video you see a similar creature called a salp which is closely related, but they are not bioluminescent. The salp moves by pumping water through its body in pulses, rather than continuously pushing it through as the pyrosomes do.
Check out the giant pyrosome and the salp in the video below: