What is this on rock

[HJWJR]

 

[Joe31415]

You need to tell us what you're asking about. There's a lot of stuff on that rock. Can you circle the object in question?
Also, I'm not sure it's an issue here, but in general setting your lights to all-white or using a bright flashlight makes identifying things a lot easier since your camera isn't trying to compensate for all the blue.

 

[BristleWormHater]

(Black) Sponge, possibly tunicates. Both are harmless
(Red) Red coralline algae
(Purple) Purple coralline algae