Answer:
They are toothy nocturnal immortals.
Humans have two that shrink in the light and expand in the dark
What is always on its way but never arrives?
What is so delicate that saying its name breaks it?
Some keep it in a dumpster while others keep it in their trunk.
I spend most of my day eating white. When I am quick enough I get rewarded with fruit and something blue. In a dark room with blue walls I run from the ghosts that roam the halls