Its body consists of a proboscis armed with hooks which it uses to pierce and hold the gut wall of its host, and a long trunk.

It was originally named Echinorhynchus semoni by Linstow in 1898,[2] and then moved to Gigantorhynchus by Porta in 1908[3] and Johnston in 1909, later moved to Prosthenorchis by Travassos in 1917,[4] then renamed Moniliformis semoni by Johnston and Edmonds in 1952[5] before taking the present name and genus by Schmidt and Edmonds in 1989.

[7] Linstow named the species semoni after the German zoologist who discovered it, Richard Semon.

[2] The morphological traits of a simple, double-walled proboscis receptacle, eight cement glands (which are used to temporarily close the posterior end of the female after copulation) each with a giant nucleus, the brain at the posterior end of proboscis receptacle, and dorsal and ventral lacunar canals place this genus confidently in the order Moniliformida.

The genus Australiformis Schmidt and Edmonds, 1989 was created for Moniliformis semoni as this species differed from other species in Moniliformis and the other genera of the family Moniliformidae, Promoniliformis, because it lacked spiral muscles in the outer wall of the proboscis receptacle.

[1] The National Center for Biotechnology Information does not indicate that any phylogenetic analysis has been published on Australiformis that would confirm its position as a unique genus in the family Moniliformidae.

Males have eight oval cement glands, each with a single giant nucleus, and possess a Saefftigen's pouch just behind the testes.

A. semoni has been found in several states of Australia, including Queensland, New South Wales, and Tasmania.

A. semoni infests these hosts by using hooks on their proboscis to pierce and hold the wall of the small and large intestines.

This infestation, which all observed cases contained 5 or fewer individual worms, may cause debilitating ulcerative granulomatous gastritis, a form of gastritis (inflammation of the stomach) characterised by ulcers and granuloma (an aggregation of macrophages that forms in response to chronic inflammation).

[1] There are no reported cases of A. semoni infesting humans in the English language medical literature.