They're legumes that grow underground and trigger nut allergies. They are the platypus of the plant world.

I don't know why I remember this, but there was also a Spongebob episode that showed a potted peanut plant with peanuts growing on it like peas do.

I guess they get their name because they're in pods like peas but without being told

Presumably the opposite; they get their name because they're in shells like nuts

(The 'pea' part is because they're a legume; it could have just as easily ended up 'bean-nut', except that would over time become 'beanut', which would probably re-become peanut)

Yes, okay, guessing the origin from the name can be somewhat misleading. But the striking thing for me is that people do not know and do not bother to ask themselves where a product that they consume every day or every week comes from. That's ignorance.