Answer:
Only two backbones and thousands of ribs.
As beautiful as the setting sun, as delicate as the morning dew. An angel's dusting from the stars. That can turn the Earth into a frosted moon.
In the evening I'm long, in the morning I'm small; When seen in a ballroom, I'm nothing at all.
My love, when I gaze on thy beautiful face. Careering along, yet always in place, the thought has often come into my mind. If I ever shall see thy glorious behind.
What flies without wings? What passes all things? What mends all sorrow? What brings the morrow?
My days are numbered. What am I?