2 part question

[jarrette]

1. I got this rock a couple months ago as a bargain basement $10 buy @ aquarium designs and the little corals have spread, but they seem like they hardly ever open up. Is there a reason for this? The insides have a really nice bright green coloring, is there an official name for these guys?

2. Also notice how much hair algae (is that the right name?) and macro has grown on the rock in 2 month in my tank. Is this a problem for a cleaner crew to solve? Is there a deeper issue with water quality that is causing the growth? Is the growth neccesarily a bad thing?