Yep. It eats the coraline off the rocks. Other than that it pretty cool. Actually, I have a pincushion that's more fun to watch because it moves around alot.
It is not normal. How old is your tank? What are your SPECIFIC water parameters? How long did you acclimate it?
THis is a sign of osmotic shock. It may be able to recover if conditions are ideal...
Not normal for spines to fall off. that means he's sick or stressed. I had mine for over a year and never lost any spines. They are great to keep as long as you do not have corals or anemones. They eat all of that.