Strange white growths (eggs?) on back wall

[JCJones]

Hi all,
We have set up our 275 cube with various coral, two urchins and a pair of redline cleaner shrimp. We have noticed many white growths on the back wall, see picture. Any ideas what they are?
Should I try and get rid of them?

 

[rako1]

I think they call them pineapple sponges they are ok

 

[rako1]

How old is your tank?

 

[gacolt]

+1 on the sponge

 

[JCJones]

It was cycling for about 2 months and has had livestock in it for about 4 months

Sorry about the dodgy photo, it's having sunset at the moment.

 

[rako1]

Your tank is still young they usually show up around 6 months do you use RODI with a silica buster DI cartridge I have read that they come from silica in tap water.
SilicaBuster DI Cartridge - Color-Indicating SuperDI? 10-inch