Technically, your body is full of tiny creatures already. Bacteria, viruses and so on. So really, should we get freaked out when we find out that there’s a specific kind of worm that lives under our skin? And should it really bother us that said worm can grow to be longer than your leg?

This brings us to the guinea worm. It starts small, really small. It begins life as a microscopic larva tiny enough to fit inside of the common water flea. Like the elderly residents of Florida, water fleas love to hang out in stagnant pools of water, gossiping and doing water exercises until they are unknowingly ingested by big, thirsty, humans.

So you go swimming and the flea makes its way down your throat. Now, not being adequately equipped to survive the harsh environment of the human stomach, the water flea is dissolved away, leaving the guinea worm larva behind. It finds a soft, fleshy cavity to burrow into and starts growing.

And growing.

About a year after infection, the full sized guinea worm is no longer microscopic, but instead measures two to three feet long. As long as a three year-old human child.

Being so large, a cramped human body is no longer adequate real estate. So the worm wants to get out, and here’s where it gets even weirder. The worm burrows to the surface of the skin and creates a blister, and causes a burning sensation. It does this on purpose, because the worm has figured out that a burning feeling in a limb makes humans want to dunk it in water.

This is exactly what the worm wants. It pokes its wriggling head out of the blister, and releases its foul, milky brew into the water, containing hundreds of thousands more larvae. They are promptly eaten by water fleas and the whole thing starts all over again.