What type of nut can not be sold in its shell?

i think an almond.

It is not an almond. I have bought almonds in the shell. The outside of an almond shell is soft and some of it is kind of powdery.

The shell of the cashew contains urushiol, a poison which is found in poison ivy and some other plants. Therefore cashews are never sold in the shell. Do a google search on "urushiol cashew"