Thinking about it it would make sense that it was forces of klipa that took over the bodies, not shedim because shedim are beings on their own.
They were created last second on erev shabbos in the six days of creation and need to eat and drink like humans, but can change their appearance. Their feet look like chickens get and are the only thing they can’t change. they also have access to spiritual realms that regular humans don’t.