Large brown bubble - algae?

[SWnewbie]

Hello All and Happy New Year!

Looking for some help to ID this odd form of what appears to be bubble algae. I noticed it growing alone next to my zoas and out of curiosity alone to see what it does I left it for about a month. This is what it looks like now and does not appear like the typical green bubble algae that I see some much of on the forums. It's probably about 3 inches wide and two inches tall. It has always been this same amber-ish color.

I wanted to know if there is a name for it and if I should keep or toss it?

My phosphates are around 0.05 and Nitrates around 5.

Thanks in advance!

 

[Lavey29]

Did it come in on live ocean rock?

 

[SWnewbie]

Did it come in on live ocean rock?

It did not. The only rock I have was a dry one I bought from LFS when the tank was first setup in March 2022.

 

[ISpeakForTheSeas]

It did not. The only rock I have was a dry one I bought from LFS when the tank was first setup in March 2022.

I have no idea what it is - there are two other threads I've seen with similar looking (to me at least) specimens though. In one of the threads it's suggested to be a sponge or Ulva lactuca - I personally find both of these suggestions to be doubtful (particularly the sponge), but I would guess it's a macroalgae of some kind. White light pics may help with the ID, but I don't know macroalgae very well at this point, though, so @WheatToast any thoughts?

The threads:
https://www.reef2reef.com/threads/brown-bubble-algae.366277/https://www.reef2reef.com/threads/giant-bubble-algae-id-m.594325/
Edit: just to add, if it isn't spreading, it may not be a pest algae.