How fast do they grow

Pictured below is a frag that I got from sharkbait a few weeks ago. I think it is some kind of Zoa. How fast do they normally grow? The pictue below is when I first got it. It now has about 10 little polyps now and has already starting to attach itself to the live rock in the tank. The little piece of rock it came with is now completely covered. Is this normal? I am not complaining just that it seems to be going crazy with growth. I will get a picture with the growth up as soon as I can.

 

Yep it's completely normal. Zoanthids tend to grow and spread rapidly. But from two to ten polyps in two weeks, that's amazing

 

In my experience it varies from frag to frag, colony to colony. Some seem to spread rapidly for me and some don't seem to do as well. I'm guessing it has something to do with the exact environment or species or something like that.
I've also found some zoas and some types of coral generally sometimes have a burst of growth after being fragged, some sort of survival mechanism I'm guessing when they get damaged they go through a growth burst to try and keep them from getting wiped out entirely or something like that.
Sounds like you have a nice start to a little colony.

 

cool, i need to get some of those... ( need to wait for some weeks though)

 

The first pic in this thread nis when i got the frag 3 weeks ago. Below is how it looks today.