The biggest bacteria ever discovered are the size of an eyelash The largest bacteria known to science have been discovered in the Caribbean. They're visible to the naked eye and surprisingly complex.

Think all bacteria are microscopic? Tell that to these centimeter-long monsters

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Bacteria are usually microscopic. Now, scientists have one that's so big, it's visible to the naked eye. NPR's Nell Greenfieldboyce reports.

NELL GREENFIELDBOYCE, BYLINE: These bacteria were found in the mangrove swamps of the Caribbean. They somehow attach themselves to sunken leaves. The bacteria look like white filaments or hairs. Jean-Marie Volland is with the Laboratory for Research in Complex Systems in California. He says each one can be about a centimeter long.

JEAN-MARIE VOLLAND: The bacteria that we discovered have roughly the shape and the size of an eyelash, and yet it is a single bacterial cell.

GREENFIELDBOYCE: He says these bacteria, now named Thiomargarita magnifica, are by far the largest known, about 5,000 times larger than most bacteria.

VOLLAND: And to put things into perspective, it is the equivalent for us humans to encounter another human who would be as tall as the Mount Everest.

GREENFIELDBOYCE: The find is described in the journal Science. And these bacteria aren't just large. They're special in other ways, too. They organize their innards in a sophisticated way, wrapping up their genetic material rather than letting it float around freely like other bacteria do. And even though their shape is long and thin, they aren't fragile. Volland says he can pick up a single bacterium with tweezers and it's fine.

VOLLAND: It is very interesting to see how strong it is. And that is something we should look into, you know, at the molecular level to understand what is behind this.

GREENFIELDBOYCE: It's just one of many things the researchers hope to study going forward. So far, no one knows why these bacteria grow so big or what advantage it might give them in their underwater home. Nell Greenfieldboyce, NPR News.

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