There's a lot to be nervous about when you're swimming in the ocean. Rip tides, sharks, crabs pinching your toes — just to name a few.

But there's a fearsome ocean dweller out there that is extremely tiny and incredibly dangerous. If it stings you, the pain can be so bad you may literally beg for death.

This creature's venom is also known for giving victims an impending sense of doom.

Here's how one person felt after being stung:

"I just wanted to take my skin off. I just couldn't be in my own skin and everything just hurt. Like your body feels like it is betraying you."

Did I mention it was tiny? And also, kind of clear so maybe really hard to see in the ocean water?

A tiny but fully grown deadly Irukandji jellyfish lies next to match sticks for size comparison in a research laboratory at James Cook University in Cairns, Australia, Thursday, April 18, 2002. (Brian Cassey/AP)

You may have heard of this creature before — the Irukandji jellyfish. It is, as you can see from above, the size of a matchstick head. If you get stung, it is the worst.

In this week's episode, Amory and Ben spoke to Jamie Seymour, an associate professor at James Cook University in Queensland, Australia, in the Australian Institute of Tropical Health and Medicine. He and his research partner Teresa Carrette study toxinology.

They've both been stung by Irukandji more than once. Jamie has been stung at least 10 times.

(If you don't spend time in waters between the Tropic of Cancer and the Tropic of Capricorn, don't worry — the Irukandji aren't outside of that zone...yet).

Irukandji are a type of box jellyfish, and the types vary wildly. People's reactions to stings also vary wildly. Most people don't die, but they spend 12 to 24 hours in the worst pain they've ever experienced. (For the ladies out there wondering — Yes, Teresa Carrette told us it's worse than childbirth.)

"For an Irukandji, the venom basically doesn't end up in your veins or arteries. It ends up in what's referred to as the interstitial spaces between your cells. It's got to diffuse into the system. The interesting thing is, if we take Irukandji venom and inject it directly into the veins or arteries of a mouse, we can kill that mouse in five to 10 seconds," says Jamie.

Another thing that can give you a sense of impending doom is ingesting large amounts of nutmeg. Ben and Amory gave this a shot. You'll have to listen to the episode to hear how it turned out...

DOOOOOMED

If you're feeling frisky, you can watch Jamie react after one of the times he got stung, here.

Unsurprisingly, people in Australia, and people visiting Australia, are extremely nervous about swimming in waters that could be full of Irukandji. If there's even a whiff of a rumor of Irukandji sitings, the beaches clear out.

Despite the risk, Teresa and Jamie continue to study them, both for the safety of the public, and with the hope that, someday, their venom can be used to treat inflammatory diseases like asthma.

In the meantime, be careful out there.