Urechis caupo

Urechis caupo is a species of spoon worm in the family Urechidae, commonly known as the innkeeper echiuran, the fat innkeeper worm (because their tunnels often contain other animals), the innkeeper worm, or the penis fish. It is found in shallow water on the west coast of North America, between southern Oregon and Baja California, where it forms a U-shaped burrow in the sediment and feeds on plankton using a mucus net.