Supposedly, the appearance of Moonlighting can give the fish a more realistic sense of being in the ocean, but you'd have to ask them to be sure of that. :thinking:
IMO, its mostly for appearance. But they do look cool!!
OH!! and dont blow $150 on some premade one. Go to the DIY section and you can make one, as I did....for like $5. That does the same exact thing, if not more.