It’s everywhere in my tank, this was just the easiest place to take pictures of it. It doesn’t seem to be hurting anything but my urchin, snails, crabs, and peppermint shrimp don’t care about eating it
The pineapple sponges? Those are a really good thing. They help filter organics out of the water. I love that they have gone crazy in my sump. Nothing to worry about, really. Just means you have a stable tank