Thanks for taking the photo Rev.
OP?
I still can't imagine it going down the hole......maybe laying under the trunk mat....maybe never there.....if it did get in the tank I can't imagine it obstructing anything...assume there is a filter screen at the pickup.
Rob
I'd stick a finger inside the filler neck and see if you can feel it lodged inside of there. It looks like the ring seals on the inside of the tube, so if it stuck when you removed the cap, it might still be located inside of the neck. You could probably get by without the seal, but concerns might be if enough environmental moisture condensed in the area to dilute the DEF (unlikely, though, I'd think) or if you drove on a lot of bumpy roads that resulted in so much leakage that it became a corrosion problem inside the trunk. I don't think I'd bother with a whole new cap, though. If you take the cap into a fleet-farm type store with you and go over to their hardware section where the drawers of washers, clips, clamps, 0-rings and other miscellaneous parts are, there's probably one there for less than a dollar that you can stick in there.