It is commonly known that walnuts are very healthy (unless of course you have a nut allergy) but did you also know that... 
1. The walnut is technically not true botanical nut, it is actually the seed of a drupe; a drupe is a type of fruit in which an outer flesh (the husk or hull) surrounds a shell with a seed inside.
2. The Greeks called walnuts "karyon", meaning head, for the obvious reason that the shell resembles a skull and the kernel a brain. 
3. Walnut husks can be used to make ink for writing and drawing; it is thought to have been used by some of the great artists in history, including da Vinci and Rembrandt.