Kill the germs, for sure, and then crush them. If you find a good way to do it, please post. I have access to clam shells, and I've been putting them in a bag and smashing them with a hammer. Pieces fly everywhere, the bag gets destroyed, etc.... I am thinking of making a tamper out of a soup can, rake handle, and cement. Don protective eyewear, put a few shells in a larger juice can, and start pounding away! Please note that this crushing method is all in my head. I have no idea if it will work. I'm thinking I'll have to bolt the big can to a board that I can stand on to keep it from falling over. I'm also thinking that I'll pull the tamper out too far and slam it down on the edge of the big can (or my foot). Might have to make it taller somehow.......