What looks like a large inflatable tube is actually a pyrosome. And while it appears to be one behemoth creature, it is actually many hundreds or thousands of animals called zooids embedded in a gelatinous tube.
“One long pyrosome is actually a collection of thousands of clones, with each individual capable of copying itself and adding to the colony,” writes marine biologist Rebecca Helm in Deep Sea News.
The creature's name means “fiery body” due to its bioluminescence, a bright green-blue glow that can light up the colony when disturbed. This intense light even inspired 19th century scientist Thomas Huxley to write, “I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white-hot cylinders in the water.”
These “cylinders in the water” can grow to formidable sizes, sometimes exceeding 12 meters (40 ft) in length. Each zooid feeds by sucking in water, filtering small particles and blowing the waste back out. This is also the method that propels the colony into motion, albeit at a very slow pace. When the zooids pause this process, the colony can sink 500-700 (1,640-2,295 ft) meters below the surface of the sea, according to New Scientist.