Pineapple looking thing

[TheWalkman99]

was looking in the back chamber of my AIO just making sure a fish didn’t jump that I couldn’t find. He popped it soon as I sat down to right this. Out spotted this thing is the back chamber I keep live rock in.
Sorta looks like a pineapple

 

[James M]

Pineapple sponges. Harmless filter feeders

 

[shred5]

Pineapple sponge

 

[Matt Carden]

Pineapple sponge

Spongebob's house!

 

[TheWalkman99]

Spongebob's house!

Hahahaha
Thanks for the replies. Knew I saw it somewhere before but didn’t think it was in R2R identification guide for some reason.

 

[Oscaror]

was looking in the back chamber of my AIO just making sure a fish didn’t jump that I couldn’t find. He popped it soon as I sat down to right this. Out spotted this thing is the back chamber I keep live rock in.
Sorta looks like a pineapple

Pineapple sponge!

Spongebob's house!

I never realized this...