what is the foliage of a sago palm pup?

Question

Is it the hard outer shell of the bulb?

Answer 1

The new heads or offshoots located on the trunk are pups. This article will tell you how to remove them and repot them (bottom of article):
https://www.gardeningknowhow.com/ornamental/trees/sago-palm/prune-sago-palm.htm

This article may help as well: https://www.gardeningknowhow.com/ornamental/trees/palms-trees/propagate-palm-pups.htm