No one has actually seen it, but a fairy interpreter asked a fairy and they described it as just a cloud of smoke and once in a while you trip over something in the floor.  The fairies purposely leave their trash in the floor because they think it is funny when people trip over them.
Inside the fairies church, Inside Church
cricket
fairy interpreter
I live in the fantasy world.  I love to be a means of communication.  I love to help.
You are the strangest fairy I've ever seen! I am not a fairy! A little brown fairy with strange veiny fairy wings! My my...but I can barely understand you! Please talk softer. They will find me and take me off. They think I am lucky. I am not a fairy. Then what are you, my new friend? A cricket.What's with the smoke and trash everywhere? I'm sorry, do YOU clean your place every day? No. But aren't fairies known for cleanness? You'd be surprised what they do when noone's watching. What kind of building is this? A noble fairy church that has a lot of trash. Are you going mad? I'm getting there.