What are these guys

[library 112]

What are these little white cones. They are on the under sides of most of my rock work and in my sump as the picture shows in the back corner. I don’t think the are harmful but can’t find any pictures that look similar. The retract and stiffen when touched. Easily brushed off. Thanks

 

[TheMetalReefs]

pineapple sponges

 

[NonstopSoda]

Yep looks like pineapple sponges! Also I like your mustache!

 

[library 112]

Yep looks like pineapple sponges! Also I like your mustache!

Thanks & thanks lol