All natural raw frozen marrow bones Nature's Variety Prairie Brand Raw Frozen Bones are fresh frozen and vacuum packaged. They are perfect for fasting days or for a special, nutritious treat that satisfies the natural chewing desire of pets. Raw Frozen Bones also supply additional quality protein, fat, amino acids, vitamins, minerals, as well as a natural source of glucosamine, chondroitin, collagen and calcium for healthier joints and connective tissue.