what is this green thing?

money plant. halimedia

 

looks like a form of macro algae. not sure which one tho

 

Halimeda, good for your tank, will remove nitrate and phosphate. Just trim it like a house plant every once in a while.

 

It is Halameda, here is some in my Biocube;


You may want to grab it as close to the base as possible and pull it out firmly but slowly and the root will come out (long white strands) and you can replant somewhere else in the tank. You don't want to shove it into the substrate but rather lay it and put a little substrate over it, it will grow down and anchor itself.