A few IDs needed

[zdrc]

I posted about these before, but the answer was kinda inconclusive. What are these yellow guys? Kind of look/behave like tunicates, but I can't shake the feeling that they're literally growing into and throughout the live rock like mycelium.

Also, what are these black guys? Looks like a sponge. Doesn't move, and I swear I had one large one mytosis into a few small ones.

Finally, I have some coralline(?) that appears to fluoresce a scarlet color. Is this just some unknown coralline?

 

[Rick's Reviews]

Sorry I'm still learning, I can not wait to find out, thank you for great pictures, really helps, I'm sure the community will provide best answers

 

[EeyoreIsMySpiritAnimal]

Someone else posted recently about the "black things"...
Thread 'Mysterious critter growing on egg crate in frag tank?' https://www.reef2reef.com/threads/mysterious-critter-growing-on-egg-crate-in-frag-tank.914584/