Where can I find desktop backgrounds that like move?

Well, I remember when I was at work...I saw my boses laptop that had a background that had actuall moving fishes on her computer screen! where can I find a site like that? I want a background for my laptop like that too! Does anyone know where I can find? No spyware, but safe! And free. Anyone know?|||Just do a search for animated gifs and you will find plenty. I recommend against having a animated gif as a background (especially in Windows) as it takes up unnecessary resources and can add to the number of things that slow your computer down.