So I just bought my first sea urchin a white pincushion. Have literally 0 nitrates in the tank. Drip acclimated him for 40 minutes. When I put him in the tank he didn't want to move but his white tendrils were moving. Slowly over the day he's been losing more spines so I moved him and put him on top of some algae. Still no movement. Today I come out and he has a white film on him and some parts have turned brown on his white body. He still has a beak but I don't know what's going on so if anyone can help I would appreciate it