This tubeworm was found growing on a small pier at Port Sonoma.   This specimen was identified by Leslie H. Harris of the Natural History Museum Los Angeles County, and photographed by Luis A. Solorzano.

This photograph of F. enigmaticus was taken by Steven Kendall along the Petaluma River.

The tubeworm growing on a small pier at Port Sonoma was removed for photography.   This specimen was identified by Leslie H. Harris of the Natural History Museum Los Angeles County, and photographed by Luis A. Solorzano.

Close up of the tubeworm tubes.  This specimen was identified by Leslie H. Harris of the Natural History Museum Los Angeles County, and photographed by Luis A. Solorzano.  The flaring rings on the tubes are characteristic for the species.

A complete picture of the worm outside of the tube.  The fans are starting to open.

A close-up picture of the worm outside of the tube.  The fans and  operculum are visible.

The photograph shows the operculum, a modified radiole (not fan) which is used to block the tube opening so predators can't get in and also to decreases water loss when the tubes are exposed.  The black spines on the operculum are characteristic for the species.   The radioles themselves are used for both food gathering & respiration.