Growth on rocks in nano

[papimelo]

Hi everyone! I have a 6 month old 20 gallon nano tank with just 2 anenomes and a diamond goby , couple snails, hermits and sexy shrimp. Saw this growth in 4 different places on the rock and would be helpful to
Know what it is and what i should do about it, if anything. Thanks in advance!

 

[ISpeakForTheSeas]

Pineapple sponges - common and harmless filter feeders. They typically boom then bust in population, going away on their own after a while.

 

[papimelo]

Pineapple sponges - common and harmless filter feeders. They typically boom then bust in population, going away on their own after a while.

Awesome! Thank you so much!