christmas tree worm
Alternative names: Spirobranchus giganteus
The Christmas tree worm is a is a tube-building polychaete worm with a segmented body of about 3.8 cm/1.5 in. They are widely distributed throughout the world's tropical oceans
Each worm has two "crowns" shaped like Christmas trees. These are actually appendages used for respiration and feeding.
Most of the Christmas tree worm's body is not visible, as it's buried in live coral. When startled, the worms quickly retract into the burrows.