Hairy Crab
 

For the longest time i have not been able to keep corals in one of my smaller tanks. They would not live for more than a month or 2. Fish do fine. I found a hairy crab or teddy bear crab in one of the rocks. Big too about 1.5". and yes is now dead.
I cant get a good picture of it .

I know they are bad but can they do damage to corals?

will be a good food for my mantis shrimp if it's still alive.