[W126 Coupe] What is this part?

[Shayegan, Richard]

I found this part in the left rear corner (i.e. corner all the way on the passenger side, closest to the cabin) of my engine bay after replacing my spark plugs (I had put the hood in the full vertical position to do the plugs). Any idea what it could be? It's plastic, painted body color on one side, and does not appear that it could be load bearing. http://Davidson.smugmug.com/gallery/1697437/1/8345092
Thanks in advance,
Richard