How do these things survive? I'll be honest, I thought I've looking at a shell for the past 6 months. Look at the tank every day...did it move....maybe it moved...maybe urchin just moved it... The other day the urchin got on it and it woke up! It tried to get the urchin off with a couple jerks. Urchin moved on and the conch hasn't moved since. What the... How is it surviving? I've been reading they do this but, what is it eating?