The Hard Tube Coco Worm, also known as the Hard Tube Feather Duster, Protula Tubeworm, or Hard Tubeworm, has a crown that can be white, yellow, orange, pink, or red.

The radioles may be banded or patterned. Younger Hard Tube Coco Worms have bi-lobed crowns, while the crowns of older individuals are spiraled