What is this

[Nick Marchese]

Picked up some Zoa and wondering what is on the rock

 

[fragit]

Little tube worms, think they are called spiral worms?

 

[Baby Ray]

fragit is right.
I have some in my tank too. They send out little feeding tentacles. They aren't too harmful but they can be invasive. It would be best to take the rock out of the water and crush them.
Hope this helps