My co-workers and I are completely stumped. What is the object pictured below?





Every time we walk by it, we stop to discuss what it could possibly be, and no one has hit upon anything that seems sensible.

It's placed between two driveways, the lower circular plate is fixed, and the upper circular plate is attached to some kind of motorized positioning jobbie. The lower plate is a somewhat lustrous white (not mirrored), and the upper plate is flat white.

We have compiled a lengthy list of conjectures, but I'm wondering if someone actually knows...

WHAT ON EARTH IS THIS THING?!