I used to have a colony of fans that covered half the floor of my tank. They've been recolonizing the last couple years and are starting to spread out into the light. The piece of dead coral on the left is covered on the back and the fans you see are new, they've started spreading around the front. Pretty soon that whole corner of the tank will be covered.
The fans really spread when hatches come off. The whole tank will be swimming with tiny baby shrimp that eventually all get ate by the fans and coral and other critters growing in the live rock. It's cool.
