aluminium plate under neuvo

getting the van ready for this years MoT I noticed, lying under the van,  an aluminium plate about 2mm thick and a foot square it is painted mat black on one side and the other side is liberally smeared with what looks like silicone adhesive - its still tacky.

Im almost certain that this has fallen off the underside of the van but can find no trace of where it belongs.

Any one got any ideas what it is, where it came from, and if its important?

If the van was parked up it can only have dropped in the vertical plane. What is there on the van above where it dropped? A photo would help.

Peter

the plate was more or less below the water tank but the bottom of the tank isnt big enough to house it (well it is but there is a great big drain cap in the middle and no coresponding hole in the plate)

I cant really take a photograph of where it fell from because I dont know where it fell from and I dont think that there is much to be gained by taking a photo of a square(ish) ally plate matt black on one side and covered with adhesive on the other.

At the minute I am favouring it having been stuck to the front vertical face of the water tank as some sort of guard but it isnt really the right size and if I had designed it to go there I would have bent it around the bottom edge to better protect that area.