I think this is mold, it may be something even better. In May, I was gung ho paper girl, but with the end of the school year and the start of summer I forgot some stuff, like this. It was fabric scraps sitting in soda ash and dye, what it now is your guess. Looks like it has been retting, I think it is done. I will give it a good wash and throw it in to the critter, my next batch of paper is purple, I hope.