That last pic has my little wheels turning. My first thought was hydroid, except most hydroids don't retract and I can't think of a branching one that does. Then the placement of the fronds, if you will, look peculiar. They are too perfect.... and where you would expect the "stem" to meet on the rock surface, they dive into a hole. It's hard to explain what I mean..... But with all those hitchhiker mollusks around I wouldn't be surprised if it were some sort of suspension feeder.... reminds me of a cuke but I don't think they stay permanetly in holes.... but maybe there is a variety that does.
The red thing looks like a mushroom because of the mouth looking thing in the center. What does it do when you touch it? What does it feel like? Does it retract at night?