Idk what this is...

[agataoneil]

first picture is upside down, this hasi been growing on my live rock. Idk please. Thanks!

 

[Retired_AF]

It could be coraline algae, but I'm not sure from the pic. If so, thats a good thing.

I'm just learning saltwater tanks myself so I'm not the expert but at first glance thats what it looks like to me. If I'm wrong someone will point it out and educate both of us.