Macroalgae ID?

[Poshangcun]

Hi, I recently got some green macroalgae for my saltwater tank and wonder what kind of algae it is. It does not float.

 

[WheatToast]

Not Chaetomorpha. Not Chlorodesmis. Maybe it’s Cladophora (though I am highly doubtful) or Cladophoropsis (still doubtful) but it best resembles some form of undesirable nuisance algae (reminds me of pond scum). Where did you obtain this from and what was it sold to you as (assuming it was given to you with a name/you didn’t find it in the ocean)?

 

[Poshangcun]

It was sold to me as ulva intestinalis by an online vendor.