Fear is the ghost of ancient. It consumes faithless human.

Anger is a ghost.
Human is the host.

Wilier races had interbred with human race during immemorial.
Therefore no need to look for them on anywhere but in ourselves.

There are people who really believe in and fear of ghost. Some of them even are too afraid that cause their minds and senses are no longer function properly to be able to distinguish whether something is ghost or else.

Some people say that human eyeballs don’t grow since born, others say those grow a bit. Anyway, it tells me a lesson why faith hardly grows by only seeing.

Only after you've done the exorcism, then
you'll understand that ghost's also a species.