> ...especially a thicker shell that protect the nut from rancidity way
 > better than the selected varieties with thinner shells.

Just want to expand on the idea of rancidity (an often misunderstood term).
Rancidity means oxidation of fat.  This is not acutely harmful (as in food
poisoning).  However, oxidation of fats generate peroxides, a highly
reactive free radical.

Rob