The macadamia (or mac) nuts you typically find in most grocery stores come shelled, for the simple reason that most nut crackers, like the one in your kitchen drawer, are not capable of cracking open a mac nut shell. Try it sometime if you ever come across a mac nut in a shell.
For that, you need a specialized mac nut cracker costing about $100, usually available from purveyors of macadamia nuts, such as California's Gold Crown Macadamia Nut Association.
Or you can get one of these, usually quite a bit more than $100, and not available from most mac nut purveyors. This one is ours, our Hyacinth macaw parrot named Princess Tara. And yes, she is a princess. Her parents are a Duke and a Duchess.
Princess Tara can pop those mac nuts open with no problem whatsoever. For reasons we won't get into in this blog post, and unlike any other parrot, Hyacinth macaws require a 50% fat content diet. Macadamia nuts are 80% to 90% fat. Princess Tara eats a lot of macadamia nuts. As a general rule, we don't feed them to any of our other parrots.
Although unable to pop the mac nuts open like Princess Tara can, a few of our other parrots are able to drill into the mac nut shell and literally excavate the nut, such as our Ruby macaw Mr. Cracker is doing here. No small feat in itself. The other macaws just play with the mac nuts like big marbles.