macro Algae type

can anyone tell me what type of macro this is? and if it might be harmful? It grows very slow.
also what eats it?

 

I'm no expert and this is a guess, but it looks like it could be a type halimeda. If it is than it's calciferous, and needs good cal levels.

 

Looks like caulerpa nummularia or caulerpa racemosa var. peltata (disc caulerpa)

http://www.usc.edu/org/seagrant/caulerpa/SpeciesKey/disc.html

This algae is invasive and can become a nuisance. The good thing is that it's easily removable compared to other macros. Also, my clowns take a bite out of it every once in a while.

 

Yep thats it - thank you

 

If you don't have anything eating it, keep it trimmed so it doesn't go sexual and nuke your tank. I lost a tank from that.

 

No problemo.