These colorful tree-shaped tube-dwelling worms live in most tropical reefs around the world. They are called Christmas Tree Worms. They live inside the reef and come out like this. Looks like smal trees. They are magnificent with twin spirals of plumes used for feeding and respiration. They are very sensitive to disturbances. They retract lightning fast into their burrows at the slightest touch or passing shadow. So when photographing you must take great care and move very slowly. Getting close is sometimes difficult and they are gone in the blink of an eye. They typically re-emerge a minute later, very slowly, to test the water before fully extending their plumes.
It is also interesting just to watch them for a while. They stay like this for long period collecting food from the water passing. These photos are from Koh Tao, Thailand. Taken in shallow water.
Read more about how I photograph macro under water: http://reflections.no/photographing-macro/