Can anyone ID this stuff growing on my rocks? Some type of sponge/filter feeder maybe a pest? (PIC)

[2Wheelsonly]

My newish frag tank is going through some ugly stages but before I start cleaning my rocks I'd like to ID this stuff that seems to have shot off EVERYWHERE in my frag tank. I would always see this stuff growing in the sump of my display system but not like this. I realize the one in the middle is aiptasia...

These things are white/clear and never grow tentacles that are visible. Almost look like some type of sponge shaped like a crown...

 

[Timfish]

Could be anything, it's hard to say from the blue light. If you bump them do they dissapear? if so they're some species of featherduster. Sponges would be a good thing and I'd be surprised if there wasn't some.

 

[Saltyreef]

They are ball anemones.
Havent had them cause any issues in my tank.
Mostly grow in the sump rocks as you stated but i have some in the display.
Id leave them unless they bother you.

 

[KJ]

My newish frag tank is going through some ugly stages but before I start cleaning my rocks I'd like to ID this stuff that seems to have shot off EVERYWHERE in my frag tank. I would always see this stuff growing in the sump of my display system but not like this. I realize the one in the middle is aiptasia...

These things are white/clear and never grow tentacles that are visible. Almost look like some type of sponge shaped like a crown...

Colonial tunicate.