Wow! Eric took some striking photos of featherduster worms last weekend. This is Serpula columbiana, a marine worm that lives in a white calcareous tube and uses its broad fan to filter food from the surrounding water.
The round, trumpet-like structure is an opercular plug. When the fan is withdrawn into the tube, the plug seals the opening to protect the worm within.
I'm a big fan of these beautiful tubeworms, and Serpula columbiana comes in lots of different color forms, so here are two more examples:
Photographed in a large, fairly deep tidepool in the intertidal zone in Oregon. Nicely done, Eric!