Is this coralline?

[Mosinmatt]

This had been growing on my rocks I started with dry new rock. I can't rub it off and it's not slimy.

 

[Onajoyride]

If you cannot brush it off easily with a toothbrush yes it's most likely coraline. It typically starts off green on rock and then the purple will grow over the top of it. You'll probably notice small purple specks on snails or other plastic spots in your tank.

 

[0utworld]

Looks like phyto in a new tank to me.

 

[Backreefing]

It’s just algae . Coralline algae takes time and good lighting and a healthy aquarium. If after 6 months no coralline algae then troubleshoot. Get some turbo snails they will help with that green algae.