Walnuts are considered to be actual nuts along with almonds and coconuts. All of these nuts fall into the stone fruit classification along with peaches and many other types of similar fruits. The seed which is located in the middle of the fruit is essentially what makes it a stone fruit.
The nut begins to form what is referred to as a â€œstoneâ€ like in a peach, and it has a soft interior which contains a number of things, including cyanide which is in fact poisonous for people to ingest. This is why it is highly recommended that people who enjoy eating these foods stay away from the stones.