You see embedded spirals, right, of green, pinkish-orange, and blue? Incredibly, the green and the blue spirals are the same color. At first I thought Richard was pulling our collective legs, being a trickster of high magnitude. So I loaded the image in Photoshop and examined the two spirals. In the two squares displayed below, the one on the left is colored using the same color from the blue spiral, and on the right using the green spiral.

This is actually really cool!

You have to focus really hard on the lines of the "blue" spiral to see it's actually the same color as the green one. Unlike many optical illusions, it gets no easier to see it correctly after seeing it correctly the first time.

The zoomed in image from the article helps:

Political metaphor as the Waxman-Markey bill moves into the Senate?

The blue and the green | Bad Astronomy | Discover Magazine