While there is no excuse for selling falsely labelled merchandise, in and of itself, I have had no problem keeping Ilyanassa obsoleta. In fact, that is the only "nassarius" type of snail I have used, collected from Peconic Bay. They are long lived, efficient scavengers. I have never seen them attack a living, active organism, and not sure what damage they could do. My guess is that either your tube worms are dying, or perhaps they are feeding on either secretions or microbial film from the surface. I have loads of small tube worms, which they have always left alone. On the other hand, this store probably scooped up a load of them in the nearest body of salt water, and is selling them at 100% profit. Not bad, if they honestly labelled them...or at least said something like "local nassarius", but deliberate misrepresentation is simply wrong.
