Cuttlefish bone or Cuttlebone is neither a fish or bone but an internal shell from the cuttlefish which is part of the octopus and squid family called a mollusk. The cuttlebone is actually part of the "head" which keeps then buoyant and moving through out the ocean.
Cuttlebone is one of the highest natural calcium sources available that is used over many species of animals as a suppliment both is domestic/captivity and the wild. Approximately 85% of cuttlebone is pure calcium carbonate.
The most common use of cuttlebone is with domestic birds from finches to large parrots such as Macaws. Cuttlebone contains a large portion of calcium but also other trace elements including iron, potassium and zinc. With cuttlebone naturally strenghting bones, assisting with blooding clotting and more we also see the added benefit as a natural tool for beak sharpening, cleaning and generally health of the beak.
Cuttlebone is an inexpensive and safe option to provide essential nutrients without introducing artificial nutrients which can be expensive and less affective.