Once again the search function has failed me. I have a couple black/purple stains on my orange Fin Fun. No clue how they got there. It was used a couple weeks ago at an indoor pool, and when I got it out yesterday for a swim I saw these spots. Not a clue what caused it, aside from maybe I set it down on a nasty spot without knowing either at home or the pool. What can I do to remove this stain? I can post a pic later if needed.