Spirobranchus giganteus

Behavior:

Christmas tree worms are filter feeders that build their own calcium tube on live coral. The coral grows up at the same pace as the tube, leaving the worms with easy access to wave their breathing and eating structures (the source of their name) outside of the tube. These structures are retracted quickly when disturbed.

Predators:

It is believed that snapper, soldierfish, butterflyfish and crabs feed on Christmas tree worms, but this has not been well-studied.