What is this white thing?

[mikesask]

Hey so i have this rock for fragging the zoa off i picked up at the weekend with a load more. I Noticed this white thing on a bit of rock this zoa has pox also is it a egg or somthing?

Thanks [emoji2]

 

[Coralreefer1]

Can’t see too clearly, however, I’m willing to bet it’s a sponge.

 

[reef lover]

+1 sponge