Crafty: What to do with leftover pumice?

After potting my icebox tulips last night, I was left with 3/4 of a bag of pumice gravel. It’s fairly attractive stuff. I feel like there must be some way to use it instead of throwing it away. Quick, put on your Martha-Stewart-Thinking-Caps and come up with something clever!

All I can think of is to use it to decorate a diorama or model train scenery (desert of course). Both of these ideas are really terrible. I guess I can become a cactus gardener? Help!