Newbie Question - Green Plants on Rocks

[nomad1967]

Hi Everyone...

Need your advice on something. I have a 35G Red Sea Max aquarium...it's 7 weeks old. I have 2 clown fish, 7 blue hermit crabs, 5 turbo snails, some star polyps and blue/green mushrooms. I also have about 20lbs of live rock (that was cured for 5 weeks.

Over the past few weeks I have this cluster of long green plants developing on the rocks. One rock in particular has a lot of it...it almost completely covers it. I have attached pictures of the plants. Is this a natural occurance? Should I just leave it?

I check my water levels every week and do a 20% water change every 2 weeks. No problems at all with this part.

Let me know if you need more information.

Thanks again for your help

Edward