Some of these nuts are simple to de-shell, such as the pistachio. You simply wedge your fingernails in the gap where the two shells meet and once you get some leverage, you can pop open the shell, and toss it in your mouth. Easy. And others take a bit more time and effort and even the use of a tool known as a nutcracker. The walnut is known as one of the tougher nuts to crack, as the shell is much thicker and it doesn’t typically have that opening that you can pull apart.