Remember the days of the iMac? It was one of the first things Apple put out after the return of Steve Jobs. The whole idea was making computers not look like computers. This started the whole aesthetic thing that eventually lead us to the minimalist things like the iPhone and the iPad.
Anyway, now with time marching on, those old iMacs are horribly underpowered for today. Well, that and everything wears out after a while.
So what do you do with an old Mac that doesn't work? Other than throw it in a landfill? It's become part of hobby-art to make Macquariums. Which are old Macs repurposed as homes for our fishy friends. Which, of course, we all learned in Finding Nemo "Fish are Friends, Not Food!"