Friend of mine grew up in South Australia, which has some pretty unique fauna. One that he said he got the most freaked out by is called the Giant Gippsland earthworm. (
http://en.wikipedia.org/wiki/Gippsland_earthworm) This is a worm that can be 3 inches wide and 10 FEET long...
He said his garage in the house he grew up in had a dirt floor, and one of the most freak-out thing he ever saw was going out into that garage late at night with the lights out, to find this huge giant THING squirming in a mass on the floor: one of those earthworms had crawled out of the ground and was in his garage writhing and coiling on the floor. The fact that the lights weren't on and he could only see it dimly in moonlight through the windows....
Me, I think I'd have run screaming and shouting something about C'thulhu invading if I saw that. bleah.
-Arlos