Is a passport a symbol of national identity or a travel document?

Banana curve

I am in the lab, listening to the Australian Open on the BBC, eating a Banana and trying to budget for a grant.
All this multi-tasking has led my brain to wonder why the banana is shaped like a "banana"? What happened in evolution for the banana to be shaped so? Are there other fruits shaped like a banana? What protective feature does its shape confer?

Truly bizarre...