I have never cleaned a Cryptochiton, or any chiton close to that in size, but smaller chitons are very easy to clean if you don't want to save the girdle. I just dry them or alcohol-preserve them in a flattened position. Then I remove the foot and viscera with a small sharp knife. Then lay them on their backs on the bottom of a flat-bottomed plastic container of bleach. The bleach quickly dissolves all the tissue, including girdle, ligaments, etc., and you end up with 8 cleaned shell plates lying on the bottom of the container, in correct order. I assume the same method would work for larger chitons, though it would take a lot more bleach. You might want to remove as much tissue as possible with a sharp knife, prior to the bleach solution. This method is not as good for rolled chitons, as the plates end up in a pile, rather than laid out sequentially. Paul M.