Anyone know what this is?

I'm wonder if that is one of the little brackets that hold the spark plug wire loom clip to the side of the engine block. 

I don't recognize that part possibly coming off of an 81. Although I agree it looks like part of a spark plug wire heat shield.

What happened to IMG #5?

  No Biggie my pal.  We all make mistakes. You're forgiven. Math was not my best subject either. 

I had the exact same thing happen to me. I posted picture on the facebook site cause I can't seem to ever load on this one.  No one knew where it came from either, its obviously a clip of some kind mine is a little different but looks to be the same size, hoping I come across it in my assembly manual as i put it back together.

|UPDATED|2/27/2016 3:09:05 PM (AZT)|/UPDATED|

That's the part that keeps the car from exploding! Really looks like part of a heat shield. Does it have a rough edge, like it has broken off of something?

I doubt that, if its like the piece I have it is paper thin not heavy enough for any kind of heat shield
It would be awesome if someone figured it out then i would know where my clip came from

I have a 2006 Cadillac XLR.  I found a part similar to yours laying loose in the engine bay on the passenger side of my XLR, to the rear of the motor and next to the exhaust manifold.  I did a little research and I found that it clips on to a weld joint on the frame where two metal flanges are welded together.  It is supposed to protect a wire harness from rubbing up against the back of the motor and to protect the wire harness from the exhaust manifold.  On my XLR it slides down to the rear center of the car and clips over the two welded metal flanges.  It seems secure, until the next time that it vibrates off.  I have had the XLR 10 years now.  Hope this helps.