the crab is kinda iffy. yes black tips on the claws usually means bad but i've also heard that you need to look closely on the front claws. if they are pointy then it's bad if it's flat like an emerald crab then it's an algae eater and no problem. the clear tube things look more like a blue social tunicate clavelina moluccensis. must have a good supply of bacteria and needs supplemented feedings of microplanktonic foods in order to survive and grow.