Answer:
In marble halls as white as milk, lined with a skin as soft as silk. Within a fountain crystal-clear. A golden apple doth appear. No doors there are to this stronghold, yet thieves break in and steal the gold.
Crooked as a rainbow, and slick as a plate, Ten thousand horses can't pull it straight.
Has no feet, but travels far. Is literate, but not a scholar. Has no mouth, yet clearly speaks.
When the horse strokes the cat, the wood begins to sing.
I wear a red robe, with staff in hand, and a stone in my throat.
I am a band that does not perform, sing, or act. What am I?