Id?

[spec33]

What are those spiky things on the zoa frag?

 

[Lionfish Lair]

They were probably are/were hydroids.

EDIT: Oh, I missed the starfish question. Most of them are good. There's a few sparse varieties that is said to eat corals. I remove them when I see them because they all seem to eat coralline.

 

[Tahoe61]

Look like a form of Calcareous Algae to me.

 

[Reefing Madness]

Looks like tube worms