Something bite off a piece of my firefish goby. Any idea what did this? I have 2 Percula Clowns, 1 Yellow Tang, 1 Royal Gramma, 2 Cleaner Shrimps, 1 Peppermint shrimp, 2 Emerald crabs, 2 Pom Pom Crabs, red and blue hermit crabs, some turbo snails, and lots of brittle worms.