My hermit crab has hitched a ride on my star

I took him off just to be safe. When I first looked over I thought it was dropping a leg. Is it fine, normal, whatever?

 

If a star is dropping a leg, it could be reproducing on the species, but it is more likely dying. Once a star starts to fall apart it may not be good.

 

Yeah, I kinda freaked out. From the angle I was at it made it look like the hermit crab shell was a little piece attached to the arm that was just flowing in the current. He's fine now, and now my other hermit is hanging from one of my urchin's spines. What an eventful evening.