Ok...well, that makes some sense in a way. When the alkalinity took a dive in our tank a while back and wiped out all the polyp extensions all over our big GSP rock, all that was left behind was the mat. It took about 2-3 weeks before the polyps grew back, but in the mean time we observed the mat go through many changes as it healed itself. It started off very grayish looking, but as the problems in the tank resolved and the GSP healed, it started to get a light shade of purple. Right before the polyps finally showed their grassy polyps, the mat turned a purple about the same color as the purple spheres in GT's pictures. The actually grassy part of the polyp takes even longer to turn green and fill in. I love this coral, and having it sort of "burn off" on us was an interesting and scary experience!