So I know that my rays have been moving rocks, we'll yesterday I caught them in the act lol. I mean I literally watched them move golf to baseball sized rocks from one side of the tank to the other.. do you think they are just curious and playing or possibly going after some blood worms that fell in between the rocks? I have read other posts where people give their rays the gorilla dog toys with some frozen food in them to keep them busy, and I'm thinking I might give it a try... since my rays are only 6-8 inches I'm guessing I should try the small version first? what's your thoughts?