What are these? Good or bad?

[Aaron C]

These started growing on one of my live rocks. They look nice, but not sure if they are good or bad for the tank?

One pic is under blue light the other is with white light.

Thanks!

 

[JVU]

They look like clove polyps. They are coral and are pretty, but can get really invasive and aggressive. My recommendation is to eradicate them now if you can, or else keep them isolated on their own island if you want to keep them. You can find a lot of discussion about this, commonly used ways to get rid of them are with kalk paste or Aiptasia-X.

 

[sfsuphysics]

Yeah the definition of good or bad usually is whether or not you want to keep them. For instance blue clove polyps some people love the look... until they see them growing over every square inch of growable space because there's no way to actually isolate them. If I was keeping a softy tank, I'd probably keep them, but if it's an SPS dominant tank would not keep them.

 

[Kensington Reefer]

just be careful that they don’t start to grow over things you “want”
I would isolate them from the rest of the rock work