What's this growing out of the side of my bubble coral?

[Matt987]

Hello,
I'm pretty new to reef tanks and wasn't having much luck with google. Can anyone help me identify what this long, stingy thing growing out of the side of my bubble coral? It seems to be growing out the side of the skeleton, and only on this coral.

The tank is about 6 months old and I have recently upgraded the light to a Redsea LED 50
Parameters are
Salinity - 1.025
pH - 8.3
Ammonia - 0
Nitrite - 0
Nitrate - 10
Alkalinity - 7.3
Calcium - 430
Magnesium - 1480

 

[Cell]

Looks like a little piece of algae or something to me. I'd just pluck it off.

 

[MrGisonni]

Looks like caulerpa algae

 

[Terry Le]

I would say some kind of macro algae