The shell that i burn incense on needs maintenance!?

I have this shell that you burn incense or something on and it is glued on and i can't get it off. I didn't burn incense sticks, i burned this concoction my friends told me. You mix Aloes wood powder, benzoin sumatra resin incense, Rich dark copal resin incense, honey amber resin incense, and one drop of cedar wood oil. Then place it on a slab of charcoal and let it burn. Now i have the problem because all this resin and burnt charcoal is literally glued on to the shell! I was thinking about getting one of those grill scrs but we only have one and that's for food. I'd really like to not ruin the shell. Any ideas?