In addition to Flyfisha's comment, you can make your own frozen foods out of live cultures you have too! I have heard of when people hatch baby brine shrimp, what they do not feed they put into ice cube trays and then freeze it so they have a supply of frozen baby brine then! I suppose you could do this with other foods you have too. With that mussel he had been describing, when you break it down and you won't use the entire thing you can always freeze part of it in an ice cube tray. It is really the same thing as the little packets you can buy, just home-made.