Red Sea Fan fragility
Can't say it's sick but it's certainly threatened.
We picked up a nice little piece in a classic fan shape recently. It had a little green hair algae on it but I gently removed most with a pipe cleaner.
Now that it's in the tank several hermit crabs have climbed all over it (I assume they're after the algae) and broken off many of the ends. I fear it'll slowly get reduced to a nub!
I could try to put it out of reach on a frag rack I suppose, but once it's picked clean of algae might they just leave it alone?
Trust no one - The ich is out there.