Phoronis australis is a species of marine horseshoe worm in the phylum Phoronida.

It is found in shallow warm-temperate and tropical waters in the eastern Atlantic Ocean and the Indo-Pacific region and was first detected in the Mediterranean Sea in the late twentieth century.

Since the 1990s it has appeared in the Mediterranean Sea, presumably arriving via the Strait of Gibraltar as early records were from Spain.

In the Mediterranean, it is normally associated with the tube-dwelling anemone Cerianthus membranaceus, with typically, about eight individual horseshoe worms being present on the tube of each host.

[3] However, it has also been recorded as living independently in muddy coarse sand in the Mediterranean, the tube being attached to the seagrass Posidonia oceanica.