What is this?

[OneMerissa]

Hey all. Any idea what these are? From other posts it seems like colonial tunicates but I can’t find anything that looks exactly like what I have!!

 

[EeyoreIsMySpiritAnimal]

I would also say colonial tunicates. Pretty neat!!

 

[ISpeakForTheSeas]

Golden Star Tunicates (Botryllus schlosseri) or fairly close relative - beautiful but sometimes highly invasive. I usually suggest isolating them on an easily contained rock away from the rest of the rock work to be safe. If you want to help them do well:

If you want to try and help the tunicates do well, offering some phytoplankton would probably be wise. Isochrysis and Rhodomonas or a blend containing at least one of these would be my first choice. For a more intensive diet that would likely show better results, see "Table 3" in the link below:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347631/