what would you be afraid to find in a deep dark cave?

I'm not a big fan of a dark. its suffocated  me. I was always wandering what will I find in the darkness. especially in the very deep dark cave. its freaking freezing down there. there might be a slugs. a big one. with the sharp fang. it sucking blood like a vampire or a leech. it will crawling and stamp at the cave walls and drop themselves onto the preys body and suck their bloods. they're slimy. so, u can't just grab them or pull them of if they starts to sucking your blood.