My family made lobster tails and we have all the shells left. They're only the shells from the tails, and they were originally frozen. Can they still be made into stock? If so, should I roast them beforehand (as I saw in a couple recipes) or are they okay since they were cooked when the meat was cooked? Can I make it like I made chicken stock or do I have to do anything differently? Can I use shrimp tails too or would that be gross? And how much water can I use in comparison to the shells? Thanks!