I just got back from a long road trip and along with all the bugs I noticed what looked like a spot of bird doo on my roof. But it had the appearance more like a splash than a normal bird deposit. It seemed to come off with a wash but then when I was drying I noticed and lighter version of it was still kind of there. I used a little Slick but it had no effect. Clay didn't do anything to it either. In fact the only thing that seems to remove it is Scratch-X. What could this be? It happened on the way home so it wasn't on there very long. I'm wondering if something nasty from a bridge construction site dropped as I passed underneath.

 

could be another form of birdcrappage. they eat all kinds of things
and they probably ate processed cheeze or something this time.

crappage will etch paint so the only way would be to polish it off if it hasnt
gone through the clear (as you did above).

 

That was some fast etching then. Since it might have been a NY bird, I can only imagine what it might have eaten.