Shrimps, mussels, squid, pear, broccoli, spirulina commercial food, human consumption purposed multi-vitamin capsules, all mashed into pulp, mixed with gelatine dissolved in hot water and poured into ice cube molds, and put in the freezer. This ice cube form is rather important IME. If you try to cast the gelatine in a slate like form, you will have a hard time breaking a piece the size you wish later.