Calcareous Tubeworm (Serpula)
This worm is also called a fan worm, plume worm or red tube worm.
"A Linnean genus of worms, subsequently used with various restrictions, now type of the family Serpulidae. They are cephalobranchiate tubicolous annelids, inhabiting cylindrical and serpentine or tortuous calcareous tubes, often massed together in a confused heap, and attached to rocks, shells, etc. in the sea." -Whitney, 1889