planets and 70s hippie books

Moomin: "Where do you live?"
Me: Um, here in this house.
Moomin: No, what PLANET.
Me: Oh! The planet Earth.
Moomin: Me too! But sometimes I live on the Wump World.
Me: Cool. *reading mortgage contract*
Moomin: The Wumps are my friends. They were scared and they runned away from the pot-bellied monsters. They were hiding. I was not scared. I am brave. I will fight them! Ho, ha, ho, ha! Fight fight fight! *waves plastic sword*
Me: Ah... you would protect the Wumps, huh?
Moomin: *more crazed fighting of imaginary polluting corporate aliens*
Me: *mildly perturbed* Um... that's nice. I think the Wumps don't know how to fight. That's why they had to hide in the cave. They're gentle and peaceful.
Moomin: Yeah! They're my friends! I will save them! And my friends are Sophie, and Merlin, and Iz, and Pierre, and Sonora. The Pollutions and the pot-bellied monsters are NOT my friends. They are like a different kind of dragon.
Me: Yeah. They're space ships. The Pollutians are like litterbugs who throw their trash on the ground.

My son... future hippie and eco-terrorist...

The funniest part of that book is the flag of the Pollutians, which on first glance is just some stripes but on second glance is smokestacks with dirty smoke billowing out to make the horizonal stripes...