The photo of a 25cm-long, winding creature can offend some viewers if they have never known the penis fish. Penis fish have invaded the California coast before, and recently they have invaded again.
Certainly, the penis fish is neither a penis nor a fish. Urechis caupo - the scientific name of this creature - is actually a spoon-worm. They are related to segmented worms such as leeches and earthworms, but lose their body parts during evolution to become smooth. Their more polite common name is "innkeeper worm" , because they create tunnels that other creatures can live on.
This species lives in the muddy sand of shallow water.
Penis fish live in the sea. More precisely, this species floats in the mud of shallow water stretching from southern Oregon to northern Mexico, digging U-shaped caves to wriggle in it.
One end of the cave is often sealed with mucus emitted by the penis fish to make nets that catch plankton and other small food particles at high tide. The other end usually has a pile of dung, which the penis worm blows out of the tunnel by shooting a stream of water out of its anus.
With a host of other small marine life, the accommodation is quite pleasant and eats any food particles that are too thick in mucus for the taste of the "host" . Unfortunately, strong storms can drive away all of them by stirring up these caves and that's exactly what happened on recent California beaches.