Yes, the sentence "Is the moon was a ghostly galleon tossed upon cloudy seas road ribbon of moonlight over purple moor" is a metaphor. Metaphor is a figure of speech that makes an implicit comparison between two unlike things that actually have something in common. In this sentence, the moon is compared to a ghostly galleon, the cloudy seas are compared to a road, and the ribbon of moonlight is compared to a purple moor. These comparisons are made in order to create a vivid image in the reader's mind and to suggest the mysterious and ethereal nature of the moon.