My wife found a spring under the seat of her car. (99 Passat Wagon)
It's a really heavy spring, about the diameter of a finger, three palms long, half the thickness of a pencil, with a little bit of rubber around part of it. It has a long arm, and hooks on both ends, one 90 degrees from the other.
Is this part of the car?
No this is not a joke ;-)
I checked under the other seat, and I didn't see anything that looked like it. I'm hoping it isn't something some mechanic removed from another part of the car and set on the floor for "safekeeping!"
Bob