Spirobranchus giganteus

Spirobranchus giganteus, commonly called the Christmas tree worm, is a decorative marine worm found in coral reefs. It has a segmented, tube-like body that extends from a hard calcium carbonate coil, resembling a Christmas tree with colorful, feathery plumes. These plumes function as gills and feeding structures, capturing plankton from the water. The worm can retract quickly into its shell for protection. Despite their vibrant appearance, Christmas tree worms are harmless to humans and play a role in reef ecosystems by helping to filter water and provide habitat for other small marine creatures.