What is this...

[Rbarber910]

Can't figure out what these are. They're very small. The parts on the string like structure are the size of a larger copipod. They don't move except the large pieces move with the current. They don't pulse or anything that I can tell. There are multiple on the walls of my tank. Some are just a line. Some are super intricate like this one. No clue what they are. Lol.

 

[Reefing102]

I think a type of harmless hydroid but not 100%. I’ll bump this up though