There is a strange sea worm that is nicknamed "Penis Fish" because of its shape and function.
Despite their nickname, a "penis fish" is neither a penis nor a fish. It's really a type of nonsegmented marine worm native only to the Pacific Coast between Southern Oregon and Baja California, Mexico. The blob's real name is Urechis caupo but it's known more commonly as the "fat innkeeper worm."
The worm's unfortunate nicknames and its sausage shape are the results of hundreds of millions of years of building U-shaped burrows along the beach. These burrows, like all good homes, are for eating and pooping.
From the front end of its burrow, the worm coughs up a net of mucus to catch tiny seaside nibbles like plankton, bacteria and other detritus that happen to pass by. When the worm sucks this net back into its mouth, it holds onto choice morsels and tosses the rest away through the back end of its burrow. It does this by spraying a jet of water out of its butt.
Detritus that the penis fish deems unworthy may become a meal for other tiny beach denizens, such as crabs, shrimp and clams. In fact, it's common for a penis fish's burrow to host various opportunistic animals looking for a free bed and meal. This is where the worm's "fat innkeeper" nickname comes from.