The ocean is Earth's last unexplored frontier, with millions of unknown species lurking in its depths. Most of those animals, though mysterious, have recognizable features: eyes, teeth, fins. But one strange creature more closely resembles a giant, luminous condom adrift at sea. The glowing cylindrical structure floats in tropical waters and is built of hundreds, and sometimes thousands of tiny creatures. Together, the colony of animals forms the mystical glowing roll called a pyrosome.

The scale of these glowing water towers—more appropriately referred to as colonial tunicates—may make them look foreboding, but the towers are spectacular, harmless creatures that are so rarely encountered that marine researcher Rebecca Helm once called them the "unicorn of the sea." Similar to coral reefs, which are built of countless polyps and their combined exoskeletons, the pyrosome consists of a collective of tiny animals called zooids. Each creature links to one another and perpetually filters the water around it to collect and eat plankton. As the colony expels waste behind it, it propels itself along, jetting itself through the water. The remarkable size of the pyrosome can be seen in this video, in which a lucky diver comes across the rare creature.

The surface of the column has been described as feeling “fluffy,” resembling a giant grid with individual creatures linked firmly together while remaining somewhat translucent. Although the pyrosome is largely harmless, it is not recommended that you try to fool around inside one, as the only way out is the way you came. One diver reported seeing a dead penguin caught in the labyrinthine tube, apparently unable to find its way back out. Because the hermaphroditic zooids can clone themselves, a single pyrosome can theoretically live forever, as Oceana notes, provided the entire colony isn't destroyed at once. Over time, a pyrosome can grow, shrink, regenerate broken parts, or mate with another colony.

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