I have never seen such big bunches of sea tulips till now.
Pyura australis (?)
See here for another photo of it.
On the stalks of the sea tulips, there were some red lace corals (?).
And on the head of one of them, there was some articulated coralline algae. (It is just my guess based on the segmented look of it.)
This one was the third bunch I saw today.
Close-up on their stalks