Is that correct? At first, I thought insect cocoons, but it looks like it is just spreading along. That would not seem to be a cocoon. The first picture has me baffled....what is that in the very front? Insects? Insect legs? Or part of the plant? Since I am always so curious, I would open one of those big ones up to see what is inside, if anything. That may help answer the question of what it is. Or we can wait for someone who knows exactly what this is.
Also, next time, if possible, put a penny down to give scale to the photos. It helps sometimes to know the size.
On edit, I think that I did find this using The Velveteen Ocelot's suggestion of a slime mold. If you go to the bottom 4 or 5 photos here, you will see what appears to be the same thing (Fuligo septica):
http://waynesword.palomar.edu/slime1.htm
You can check by seeing if your problem is hard like cement, and if you can find the spores under the surface by scraping the surface as shown in these photos.
If this is what it is, you don't have to worry about it. It will do no harm. At least, that is what the link from TVO says.
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