what all has everyone tried to keep thier octo entertained? Right now I am keeping him occupied with new things in the tank. I put in a new shell, some clean glass vials, lids, marbles, anything clean that I am sure he can't hurt himself with. What else can I do? He is very curious and brave and connot handle anything new in his tank that he doesn't place himself. He does enjoy grabbing and tugging the net when I collect poop from his tank and grabbing my fingers when he's near the top. I really want to keep him mentally stimulated as he seems really sharp.