There are two board images of a conformally coated Engine Control Unit at:
https://www.flickr.com/photos/128859641@N02/25836586336/in/dateposted-public/
Not the best images, but would anyone care to speculate on the composition
of the star-burst patterns circled there?
Base on an even fuzzier image, I'd speculated that it was dye concentration in
an uneven curing process, but these give it a colour that suggests external
contamination of some kind, possibly bleeding into cracks.
The spikiness suggests a dendrite growth, but I don't want to get anyone excited.
RL