Cocoworm

The coco worm (Protula magnifica or Protula bispiralis) is a marine polychaete tubeworm prized for its colorful, feather-like feeding plumes. Unlike soft-tubed feather dusters, coco worms construct a rigid, protective calcium carbonate tube that can grow up to 8 inches (20 centimeters) long, from which the worm extends a pair of elaborate, spiraled crown structures called radioles in shades of bright red, pink, orange, or white. These plumes function as both gills for breathing and filter-feeding nets that trap microscopic phytoplankton and organic detritus from passing water currents. The worm is extremely sensitive to movement and light changes, rapidly snapping its plumes back inside its hard tube at the slightest sign of danger.

In a home aquarium, coco worms require a mature reef environment with moderate, non-direct water flow and targeted feedings of liquid phytoplankton or fine micro-foods. They need stable calcium and alkalinity levels to continually build their hard tubes, and they must be kept away from nipping fish species like butterflyfish, large wrasses, or angelfish that might eat their delicate plumes.