What the heck is that thing?

[eefox49]

I have an '86 (built in '85) 500SL. Something came loose behind the driver's side headlights and pushed the wheel well liner into the tire. I can just barely see through the gap between the wheel well liner and it looks like some sort of canister. I think maybe it's the supply tank for the climate control, but I'm just not sure. I would really like to know what it is before tearing into that part of the car. It's a little hard to get to. I pushed the liner off the tire and everything's fine. Maybe I'll just leave well enough alone. Any ideas???