Is this a coral ?

[craigpaterson]

Are these corals ? Will they spread ?

 

[reef lover]

I think those are feather dusters...

 

[Reefloco760]

Yep feather dusters

 

[craigpaterson]

Will they spread ?

 

[bsagea]

They will spread. Halichoeres species of wrasses like to make a meal of them. We had hundreds in one of our tanks until we introduced our checkerboard. I personally loved them and thought it made the substrate look like a garden. Don't have a one left now!
bsa

 

[George113]

Yes a feather duster. I love them. They look cool!