my pink decorated sea urchin (i think that's what it's called) has lost like 50% of it's spines for some reason and is not doing well. it keeps trying to climb up on rocks and i find it later on it's back on the sb. since i got it it refuses to eat my hair algae for some reason so i've been feeding it nori algae about every other day. it's still eating, i fed it yesterday and water quality is good i checked that yesterday. anything i can do to help it?