I've got a question about black algea. What does it look like when it dries out? I was given a used fuel filter canister (similar in nature to our oil filter canisters but for fuel) for my truck to see if I could clean it up & us it as a spare. When I opened it up & took the filter out, it had a clump of "stuff" in the bottom of the canister. It was pretty big. About the size of a "D" cell battery. It almost looked like a lump of charcoal that had been soaked in liquid until it fell appart. Is this black algea? It was black, kinda gritty, and would break appart when mushed w/ a screwdriver.