Those are Leucilla or Clathrina sponges, both more commonly called Q-tip sponges. They are not tunicates. All tunicates have two openings and Q-tips, including the ones pictured only have one. There is a common tunicate that looks very simular to them, but it has two very clear openings. I have both and once you've seen them side by side it's easier to tell the difference. The sponges are also harmless filter feeders.