need help to id this

[Der_Iron_Chef]

To be honest, I see what looks like three different types of algae there. I say pull 'em. Better safe than sorry.

[Joe Reefer]

I see a couple different algae too. The stringy type algae left of the mass is bad. Not exactly sure what it is but its a PITA to pull off rocks. I would try and get rid of all of it.

[sharuq1]

I see caulerpa on the left, some sort of stringy junk in the middle and that other stuff not sure... it could be this?
http://images.google.ca/imgres?imgurl=http://myweb.dal.ca/rescheib/codium-home.jpg&imgrefurl=http://myweb.dal.ca/rescheib/codium.html&start=42&h=200&w=200&sz=83&tbnid=xLIPE cZSob-tTM:&tbnh=104&tbnw=104&hl=en&prev=/images%3Fq%3Dcodium%26start%3D40%26um%3D1%26hl%3De n%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-USfficial%26sa%3DN&um=1
http://images.google.ca/imgres?imgurl=http://www.marineflora.com/bmz_cache/9/9ac3631cc1c6a3c35bbe4c869624f7c6.image.400x400.jpg &imgrefurl=http://www.marineflora.com/index.php%3Fmain_page%3Dproduct_info%26products_id %3D38&start=3&h=400&w=400&sz=45&tbnid=lhaO2WvtuDDK EM:&tbnh=124&tbnw=124&hl=en&prev=/images%3Fq%3D%2522macro%2Balgae%2522%26um%3D1%26hl %3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-USfficial%26sa%3DN&um=1

If it is a "codium" it says it is very invasive... =/