Thats the only way I can describe it. I washed my car for the first time in months yesterday and it felt great. But there were about 2 dime size spots of weird crud. I dunno how long its been on there but that stuff is tough. I couldn't even really scrub it off or scratch it with my finger. Whats the strongest abrasive thing I can use without harming the paint? Or does anyone have any other general useful suggestion?

 

try using a clay bar on it, and pics would be useful