what you have there is called "ogo". i don't know the latin off hand but i'll let you know. apparently it's hawaiian endemic. i have a tank full of it, it starts off growing fairly slow but once it gets going... according to an article i read it's fantastic in refugums. it's very hard to re-attatch, as you have found, cos it does have a habit of just coming away from the rock. damnhippo is right, my tank is only lit by flouro's, and have given chunks to friend that have MH's on their tanks, and it has died. count yourself lucky i think it looks great when blowing around in the water!!