What is this.

[Stevepo]

Please identify, it has been spreading rapidly of late. It started as a few stems and was nearly whipped out by turbo snail when the tank was cycling. Now it is like a Forrest.

Is this good bad or otherwise?

Regards,

Steve

 

[Craigj247]

Looks like a type of coral... Maybe flower pot... Really doubt it is anything bad for your reef...

 

[manbeast]

Hard to tell from the photo but there are many varieties of colonial polyps many of which can grow quickly and overrun a tank, I would start on google searching for different types of colonial polyps