Strange white/clear growth on rocks

[Joeyw55]

Hi
Can anyone tell me what these white/clear growths are on my rocks?

Tank has been running 18 months and never seen these before

Thanks!

 

[jeperry3]

Looks like pineapple sponges. Harmless.

 

[Joeyw55]

Thank u v much. Just googled pineapple sponges and I think you are right. Thanks again

 

[Viethuenese]

they're actually great for your water