Odor control bag of rocks- can't remember how to make them work?

Question:I bought these plastic mesh pouches a couple of years ago at Menards- a bigger one for the basment and a smaller one for the refrigerator. THey are filled with little rocks. They are supposed to be for odor control- like instead of using baking soda in the refrigerator. I remember that when I first used them they workd quite well. To get them to work again, I think the directions said to microwave them, or boil them- or something- and it would get them to work again. But, I can't remember what I was supposed to do. Anyone know what I am talking about and know how to make them work?
Thanks!!
Katie

Answers:
The bags are filled with charcoal, which absorbs odors. Simply rinse the charcoal under hot water.