What is on polyp and coral

[Saieditc]

Hello
There are this on polyps and on sps...
This grow on sps and live rock....
How do I remove it?
This is dangerous?
It cause the prevent lightning on sps and else...

 

[jeffchapok]

Clove polyps. Not dangerous, be they can be invasive and left uncontrolled can overrun your tank and choke out more desirable corals, as you can see.

I've never had them so I'll leave it to someone more experienced to chime in on what to do about them.