Mushroom color

Two weeks ago I had a mushroom in my tank. It decided to move around. I didn't try looking for it, I figured it would turn up eventually... Well this morning it turned up clear across the tank! It was under a rock and on the sand bed so I moved it a few Inches onto a rock so it was getting light. It rooted right away and opened really wide an the mouth was wide open in a few minutes. I spot fed.

When it went missing the coloration was slightly blue... Now that it has turned up, the color is bright bright green, similar to some of my zoanthids. Do you know what this transition is from?

 

I'm thinking it has accepted some zooxanthalae from the zoas is culturing the same type of algae now???