Serpulid Worm
Serpula vermicularis

A Serpulid Worm extends its feathery branchial crown
to capture both food and oxygen from the passing currents.

The visible part -- less than 1 inch (25mm) across --
is only a small portion of the animal.
The rest, which can extend another 4 inches (100mm),
stays hidden in a calcareous tube manufactured
by the worm and attached to hard substrate, such as rocks.

These worms range from San Diego to Alaska.