What to do with the eye-wateringly ugly fireplace?

[Mindy Jensen]

This is my fireplace. The mortar is dark grey, the rocks are called Moss Rock (I think) and the whole room is dark because of this space. The wood has to go, my husband HATES these rocks and wants to rip them out. I think that's a bit much, but we are stumped as to how to make them look better.

Any suggestions?