With the Chapter 2 i couldn't resist to make my version of the creature.
IT metamorphosis stage 3 of 3, Pennywise shows his real face.
The entire evolution of the monster starts from the back of the clown and keep to evolve to ITs final shape.
The idea is that IT belongs to a species of colonizing aliens that use the creatures that inhabit the planets they visit to carry on their species and produce billions of eggs.
-The metamorphosis starts from the clown's back and keeps to evolve from it, as the matter of things the back of the creature conteins the eggs.