It looks like the strangest tangle of worms, and the sight of it certainly seems to have baffled locals in the Taiwanese city of Hsinchu earlier this week – while also bringing us a few of the expected "It's-an-alien!" headlines. But this "ball of worms" is not quite what it appears to be: only a part of it is a living creature.

Commenters online initially identified the squirming mass as a group of horsehair worms (nematode-like parasites in the phylum Nematomorpha), but the bundle's jagged edges suggested otherwise. We reached out to University of New Mexico parasitologist Ben Hanelt, who confirmed that we're actually looking at just a single horsehair worm. (No aliens here, then.)

"There is indeed one hairworm in that video," he says. "The thickest part is a hairworm. It seems to be wrapped up in something else – either man-made or plant material."

Whether the bulk of the tangle is made up of plastic meshing or some other material remains a mystery (and other details surrounding the clip are sketchy, too), but if you look closely, you can follow the outline of the parasite's body from the upper right corner as it curls its way down to the lower left. 

Also known as Gordian worms, these animals pose no threat to humans or pets. Instead, they develop inside the bodies of insects like grasshoppers, crickets and cockroaches, and are typically found near small puddles and streams – or in particularly wet areas.

And while you'll most often find a single parasite per host, they do, occasionally, emerge en masse. In Wired's Absurd Creature of the Week, Matt Simon writes:

[T]he 350 or so known species invade insects ... After developing for several months, the worms mind-control their hosts to make a kamikaze dive into water, then escape through holes bored in the insect's exoskeleton. The parasites end up in a tangled knot that can be as heavy as the tattered – and oftentimes very much alive – host they leave behind. 

Horsehair worms reproduce and complete their life cycle in water, so by using mind-controlling chemicals to lure their hosts to lakes and streams, they get a free ride to their final destination.

Chances are you remember this viral clip from several years ago, in which a group of horsehair worms emerges from a cricket:


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In the case of the lone Hsinchu worm, the creature may have hit dry ground while attempting to free itself from entanglement, or it possibly found itself stranded in a dried-up puddle.

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Top header image: D. Andreas Schmidt-Rhaesa/Wikimedia Commons