Algae? Moss? ID

[zenkatydid]

This stuff is in one of my tanks. It started in one discrete spot, growing on a bit of driftwood in a clump and I thought it was an algae. It didn't seem to be invasive and wasn't unattractive, so I left it alone. I've since removed that bit of wood, and in the process seem to have strewn filaments of this stuff around the tank. Wherever a filament landed, it's grown and multiplied much like a moss. It never appears out of thin air (water?) like algae seems to do, and doesn't seem to be in response to nutrient/light changes. So, what is it? An algae or a moss?

 

[rkilling1]

That is Cladophora algae. Not that bad of a problem. If I had to choose what algae was going to grow in my tanks, I would choose this one.

More info here:

http://www.aquariumalgae.blogspot.com/

 

[theotheragentm]

http://aquariumalgae.blogspot.com/2007/06/cladophora-algae.html