Here are some images of Christmas Tree worms (Spirobranchus giganteus), just in time for the holidays:
These are tube-dwelling worms that live in coral reefs and use their spiral plumes for feeding and respiration.
Christmas Tree Worm Identification -- powered by ehow
Having spent time scuba diving in the past these worms are one of the highlights of the reef. In addition if you push water near them, they will retract their gills.
The feeding/breathing capabilities of the christmas tree structures should lead to many interesting studies!