Pest ID please

[zheka757]

What is this all over my rock work, and how do I get rid of it?
And when corals incrust on rock it looks like this

or like this

 

[Formulator]

Can’t really tell with the blue light. Can you get a photo or another video with 100% white and no blues?

 

[vetteguy53081]

What is this all over my rock work, and how do I get rid of it?
And when corals incrust on rock it looks like this

or like this

Colonial hydroids. In the future, pics best under white light intensity. You can place rock in a container of tank water and scrub/scrape them off OR smother with coral putty. They feed of suspended food and multiply as they have already