An Australian biologist has shared photos of the "penis fish", and it appears people are huge fans for perfectly mature reasons.

Urechis caupo, better known by its more phallic name for fairly obvious reasons, is a species of marine spoonworm that spends most of its life burrowed in the soft sediment of the sea bed. Also known as the "fat innkeeper worm" (these guys keep getting dragged by scientists) these worms can live under the sand for up to 25 years, minding their own business and feeding on plankton, bacteria, and other small particles that fall into their mucus traps.

They were captured and shared by Josie Jones to the Marine Research Group of the Field Naturalists Club of Victoria.

_{The comments were of course mature, and nothing to do with noting quite how much like a penis they look like.} 

These strange-looking worms create u-shaped burrows in sand or mud, then secrete a slimy mucusy net that stretches from the entrance to its mouth to suck up food. 

"Using contractions (peristalsis) to pump water through its burrow, the worm sucks plankton, bacteria, and other bits into this net," biologist Ivan Parr explained in an Ask the Naturalist piece. "When, like any vacuum, the net gets clogged, the worm slurps it all back into its mouth, taking in the particles it wants to eat and discarding the rest into the tunnel."

The animals get the name "innkeeper worm" because other creatures will often move in to the tunnels they have lovingly crafted. They get the name "penis fish" because they really, really look like a donger.

A few years ago, walkers on the shores of Drakes Beach, California, were surprised when they found thousands of the fish washed up. 

The 10-inchers (they can even grow to around 30 centimeters in length) appear to have been disturbed, picked up from their quiet life, and strewn across a beach for as far as the eye can see in this photograph snapped by local resident David Ford.

“I had no idea what they might be... it went on for two miles,” Ford told Vice. "I walked for another half hour and they were scattered everywhere. There were seagulls lined up the beach the whole way having eaten so much they could barely stand." 

Urechis has four species of penis fish. U. caupo is the only species that is found in North America; the other three are found in Asia, where they are eaten as a delicacy.

So, how did they end up getting dumped on the beach? 

"We’re seeing the risk of building your home out of sand," Parr said. "Strong storms – especially during El Niño years – are perfectly capable of laying siege to the intertidal zone, breaking apart the sediments, and leaving their contents stranded on the shore."

Poor penis fish.