What Do You Keep On Top Of Your Tank/s?

[chrisbassist]

I got a back of slate from a garden centre for my caves... absolutely filthy, but I'm pleased with it, for less than £5

 

[Mr Spoon]

Nothing on all but one, which i have 2 frogs on

 

[Joshwainwright]

My mum likes to dump her washing pile on top of my tank, of which when spotted gets thrown on the floor