I prefer the mineral blocks for several reasons.

Cuttlefish live at the bottom of the ocean, so I doubt that their bones were intended by God, or anyone else, to be for avian consumption. Yes, they are "natural," but they can also splinter and have sharp points that sometimes injure a bird. They also are nearly pure calcium with little of the other minerals that should accompany calcium for maximum absorption and usage by the body.

Mineral blocks, on the other hand, are designed specifically to meet the calcium and mineral needs of birds and to help wear their beaks down. The Manu brand in particular are formulated to have the identical content to the mineral-bearing clay that macaws and other parrots eat in the wild. Plus, a mineral block -can- perhaps break or crumble in the beak of a large macaw or cockatoo, but it can't splinter into sharp pieces.

Note from Shelly: Many breeders provide cuttlebone to breeding parrots as the calcium required to produce eggs is very great. To reduce the issue with cuttlebone splintering, one option is to place the cuttlebone inside a couple of plastic baggies (put a baggie inside a baggie and then place the cuttlebone inside that). Next, use a hammer and break up the cuttlebone into smaller pieces which can then be placed in a food bowl for the birds.