I had a red fromia starfish in my tank. While I was watching it, I noticed my first little crab-like hitchhiker in my rock. The starfish was covering a hole in which the crab was living. It kept pushing out rocks and debris from the hole but I didn't think much of it. Tonight, I got home and my starfish had one of its legs half off. I picked it up assuming it is dead and the bottom is all fleshy and torn apart. How do I really know that it is dead? I am pretty certain that it is just by the way it looks all torn apart. Any specific way?