Analyses of canned lobster for magnesium, ammonia, and inorganic and total phosphorus have indicated that the extent of crystallization of magnesium ammonium phosphate in canned lobster is limited by the concentration of magnesium. This has been confirmed by experimental canning. It has been shown by experimental canning that sea-water, the magnesium concentration of which is approximately five times that of lobster meat, is the major contributing factor in the formation of large quantities of these crystals. Abstention from the use of sea-water in any step of the canning process restricts crystal formation to the point where it escapes the observation of the consumer.