I have a 30 gal tank with somewhat new rock and no coral (waiting for water to stay stable) the tank is about seven months old. I've noticed one of my clowns making a crater by two of the three tunnel entrances I created with a Y shaped PVC pipe. She has already paired with another clown that rarely, but sometimes cleans the space as well. Is this a territory thing? Should I look into corals or anemones to give them a home? I can attempt a video if I see it happening again.