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Okay, my name is Dr. Teresa Carrette. I've spent my career so far researching the deadly and dangerous.

Hi, I'm Bill S. Straight. I'm a retired Air Force Colonel from Pittsburgh, Pennsylvania.

I've spent six tours of duty in Iraq, Afghanistan, the Horn of Africa, and what I was doing in April 2014 was going through some combat water survival training in Key West, Florida.

While I was sitting there, I started to feel all these needles stabbing my thigh and then going down to my lower extremities up and down both of my legs.

I feel like I've got hot kind of stabbing pokers being prodded into various parts of my body, like random, none of it really makes sense.

I started to have these extremely painful spasms in my lower back. At one point it felt like someone was hitting me in my lower back with a hammer.

I had sort of holes I'd scratch through, like special through my head, or like through my scalp, had kind of big marks where I managed to scratch holes in myself quite successfully.

Once it hit my spine, it literally felt like fingers were going up my spine and starting to wrap around my ribcage.

You start to get this feeling of something bad is really about to happen.

This week Endless Threads episode of Scream Time starts out a bit like a sci-fi horror movie.

Scene 1, The Scientist.

Dr. Teresa Kurett is underwater in full diving gear off the Great Barrier Reef in Australia.

She's doing difficult research because before she can do her research, she needs to find her research subject.

They are so hard to track down. They're an invisible animal in an ocean that's not even needle in a haystack, that's, you know, needle in a forest.

On today's dive, she thinks she's found the needle in a forest, which is why she's made all of the effort to protect herself from her special research subject, including diving gear, which doesn't leave an inch of skin exposed.

But the diving gear still has flaws.

We were fully covered with gloves, full suits, you know, hoods, the whole lot.

I had come up from a dive and was getting into the boat.

And as I put my hands up onto the boat, actually a bit of water washed down in between my glove and my suit.

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