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
bee
fairy
I'm a fairy that lives in the forest. I like to fly around with my siblings and play games. I try to hide from humans. If they find me, I'll grant their wishes.
What's up little bee? Have you seen any humans today? Yeah...They came to steal my honey as usual I've been hiding out from them for days. I wish they'd stop chasing me. What do they need you for? If they catch me, I grant them a wish. I'm in the church here hiding from them. Then stop granting them wishes. Humans are selfish I know, in their defense though, honey is quite delicious. Yes. But why pack it all? I never see them bothering the butterfly though. What makes him so special? Spider aid the pollination and it doesnt produce any sweet honey. Boy it's getting hot in this church, Do you mind if I take off my dress to cool off? you look disgusting! put that cloth back on.