Help Id this sponge.

[Reefforfun]

It grows under my brain coral for months. I see no harm to the coral but it seems about to encrust the whole base of the coral. Please help me id this sponge, is it harmful in a long term?

 

[Gargoyle]

I don't know but I like your tank. Is that a white crab just up and to the right of the sponge in question?

 

[Reefforfun]

The little man is anemone crab.

 

[vetteguy53081]

What a mix
top are ball anemones
3rd pic tunicates
Mid- crab