What is this small white strings?

[erfan_m_h]

Hello everyone. I start my tank 6 months ago and 3 months later I have to treat it by cupramin seachem because of ick problem and nothing added to my tank after that. From 1 month ago this little string start to grow out of my live rock. Can anybody tell me what is this small white strings on my live rock that I send in first and second images ? Maximum Size of them is about 3 to 4 millimeters and mostly growing on light spot.
And in second image what is this creature? Is that Aiptasia

 

[KJ]

Welcome to R2R!!!
Sponge.

 

[erfan_m_h]

Welcome to R2R!!!
Sponge.

Thanks. and what about another creature ?

 

[Leemcg]

Welcome !
All of them look like sponges.

 

[erfan_m_h]

Welcome !
All of them look like sponges.

Thanks . And are they bad ? If yes how to get rid of it?

 

[Leemcg]

They aren’t bad. You can pull them out if you want. Should mostly die out without any issues. Some fish and inverts eat them. I generally don’t bother with them as long as they are small and not in the way.

 

[TankCandy]

Thanks. and what about another creature ?

It looks to be a Pineapple Sponge.

 

[Glass Algae]

It looks to be a Pineapple Sponge.

+1 pineapple sponge!

 

[erfan_m_h]

Thanks everyone.