I'm almost convinced that it's because they know I want them to do it! I have all kinds of mushrooms, frogspawn, even Macro grape for them..I fig. something might appeal to them. I placed some of the grape algae in their corner..they had a fit, I thought it might be a nice bed for them..better than that scratchy sand. They weren't having it they beat it up! You should see how they attack my seahare when he goes over there to clean..they dive bomb him and he slowly goes his way..he's probably thinking what's their problem?!