Oddly enough, my wife made these decorative olive oil jars with rosemary and peppers for family for Christmas, and everything above the oil line started to mold. I was trying to come up with an idea of what to do with the olive oil, now that it isn't edible anymore. Thanks for the idea.
By the way, you can do the same thing with an orange. Peel is so you have one half of the peel with the center white piece intact. Pour olive oil into the peel cup. Let soak a few minutes, then you can light the center rind piece and it will burn for a few hours.