i had a "nuclear" green(that's nucular for you bu****es)candycane that grew to 10 polyps from 2 in about 2 years. then it fell into a brain coral, only one polyp survived. now i'm back up to 4 polyps. i would call anything over 8 heads or so a decent colony, but i've seen some MUCH larger than that, although they weren't the super bright green, they were the more common whitish blueish kind of color.