So long story short, my car blew the head gaskets... again. Bought it with them done near 100k, blew at 135k, so obviously the previous job was done by a POS mechanic.
The symptoms were, coolant was disappearing, but there was no oil in it. My friend/coworker said it was a head gasket and that he could test for exhaust gasses in the coolant... it was there.
This friend of mine has replaced 4 Subaru head gaskets and just did a WRX swap into his Forester, so I felt he's a guy I can trust to do the job.
We pulled the engine and removed the heads to find this sight...
So my questions (and his) are, what is it? Where did it come from? And what should be done about it?