limestone?

[Nautilus291]

I recently bought a rock at a pet store. But when i brought it home it lookes and feels alot like limestone, or sandstone. How bad is this for a fishtank, and what does it do.

On my receipt it says coral pagoda what the heck is that, and why are they calling a rock that.

[Fishguy2727]

If it is coral anything it is probably old dead coral in some form or another. That means it will 'help' (or hurt) bring up the pH and harden the water.