Borrow a piece of someone's live rock that has the color you want and scrape the spores in front of a powerhead to distribute them around the tank.
I have purples' and red coralline on my LR
. This color (green) only seems to be growing on my glass. This green stuff has grown over the purple I had growing on the back of my tank as well. I wonder is this type has found something in my water that it likes more than the purples and reds.
ps. you need some pics of your shrimp posted. I too am fascinated my the mantis. I am going to turn my nano into a mantis tank once I get my 100gal reef up and running.