It may look like a screen grab from a B-grade creature flick, that's a real living thing in the photo above. These hollow, worm-like entities can grow to a mammoth size. In fact, they've been recorded at lengths comparable to a sperm whale. Even more eerie, they are bioluminescent and will glow when touched — that is, if you're brave enough to swim up to one.

Encountering Giant Pyrosomes

What in the world is it? It's called a pyrosome, and although these marine monsters are rarely encountered, scientists believe our oceans may be teeming with them, according to New Scientist. The picture here was captured by divers at the Eaglehawk Dive Centre in Tasmania, Australia. You can view the video footage from the encounter here:

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Pyrosomes might look like giant sea worms, but they're actually hollow on the inside. And while they appear to be a single organism, they are colonies of individual creatures that have banded together for a common purpose. Exactly how these massive colonies coordinate their behavior is still being studied, but researchers suspect they communicate through light signaling.

The bioluminescent light shows that pyrosomes are capable of a display that's awe-inspiring, if not otherworldly. Imagine witnessing one of these light up in the ocean below while sailing at night, or while night diving. Their green-blue or red glow (the color depends on the species) radiates more intensely when disturbed, so touching them can trigger the spectacle.

Cloning and Jet Propulsion

Another interesting fact about pyrosomes is that they're jet-propelled. Their hollow inner channel sucks in water from one end and expels it out the other. It's not a powerful flow, but it's enough to gradually push them along through the ocean's currents. The sucking in and expelling of water is also how the colony captures food and disposes of waste.

Pyrosomes may also be immortal, in a sense. They reproduce by cloning, so the colony can regenerate injured parts. Though individuals in the colony die, the colony itself could theoretically live forever.

And although they are mostly harmless, if you ever encounter a pyrosome, it's not advised that you attempt to swim inside its hollow tube. According to one diver's account, a 6.5-foot specimen was once encountered with a dead penguin trapped inside.

"The penguin had obviously swum in the open end of the tube then couldn’t turn — it was jammed in the apex of the pyrosome and its beak was just poking through the colony matrix," recalled K Gowlett-Holmes to Deep Sea News. "Even fairy penguins are quite strong — the fact it could not break free shows just how tough some pyrosomes are."