Marbled Paper Pattern in Illustrator

For a book cover design, I came up with a marbled paper pattern, entirely in Adobe Illustrator. A sample of the pattern is shown below.

One nice thing about doing it this way is that I used 9 global color swatches in Illustrator. If I ever want to use this again, but in a different color scheme, I could change those swatches, and I'd be done. Even the blotches are based on the swatches, so they would update, too.