There was some poetry in those illustrations, and we wanted to keep that same feeling, Bayona says.
The tree has been always an allegory for spiritual growth, Bayona says.
The monster represents the man Conor is turning into.

Credit: Quim Vives
A Monster Callsopens in theaters on Oct. 21.
See a new photo from the film above and concept art for Neesons monster below.
