What is this?!

[CookieRdReef]

My mushroom moved away from its normal spot to reveal this bubbly egg looking stuff living behind it. Any idea what it is? Pest? Alien eggs? Thanks!

 

[Robertellis30]

Look like sponges to me.

 

[CookieRdReef]

Thanks! I was hoping sponges but I haven't seen them anywhere else in the tank. It's my first tank so I'm still learning!

 

[AcroNem]

Could be Tunicates, but also likely to be sponge

 

[Sparkymarc]

Looks like a group of pineapple sponges