A couple of things to ID

[JDMosher]

OK, I have a 150 gallon existing system that I bought, paid to have it broken down and transported to my house. I have had the tank about 9 or 10 months. There are a few things I have no clue what they are and I need help.

First let me apologize for the photos. They are not all that great.

First one I think is a baby anemone of some kind. the problem is, it never grows. It is white with green edges/tentacles and around 3/4 of an inch wide.

Second is a black blob that looks kind of like a slug but you never see it move.

Please let me know what they are.

 

[DSC reef]

Possibly a type of rock flower anemone and looks like black sponge

 

[JDMosher]

Possibly a type of rock flower anemone and looks like black sponge

I was thinking rock flower anemone but couldn't be sure, I'm too new and there are way to many possibilities. I also have something yellow that looks like the black thing half under the rocks. I hope they are sponges, wait, sponges are good right?

 

[DSC reef]

Sponges are good in general and are a sign of the tanks biodiversity. They can smother corals but are easily removed if they get to close. I prefer the yellow sponges.