Yes, they're called marimo moss balls, they help with natural filtration and bottom feeders (fnar!) can nibble off them. I was intending on getting a few shrimp (moss balls are good hiding/eating sources for them) but trialling Merlin with the snails first (they're tougher!) and although he completely ignored the snails in the pet store tank, he's pretty curious about the snail in 'his' tank, so I don't want to risk getting the shrimp if they'll effectively be food 'Artwork' is stretching it, in just going to cut a cardboard template the same size as the back of the tank and cover it with wrapping paper! That way I can change it whenever I fancy. I had one Betta that flared at ANY background; it'd really stress him out. I tried so many pictures - rock, sea, completely black, and it became a bit of a project to find 'the one'... nope, it was 'the none'