Algae growing on my rocks. Identification?

Hello. I have an interesting form of algae growing on my rocks. It's only growing on the rock, and it's growing like crazy. I'm attaching a pic, but it's not a very good one. Hopefully you can see it.

The algae looks like green coral, or like a small shrub. It is soft, because it blows around with the current in the tank. My black mollies and crystal shrimp won't touch the stuff. It looks more like some sort of moss than it does algae, but I know it's algae.

I can pull it off pretty easily with tweezers. Please take a look at the photos, and let me know if you have any ideas. Thanks so much for the help. Aaron.