Though only from a few bones, researchers suggest that Murrayglossus was the largest monotreme to have ever lived, measuring around 1 metre (3.3 ft) long and weighing around 20–30 kilograms (44–66 lb).

Augee (2006) speculates that this feature made the animal more adept at traversing through thickly wooded forests.

[2] Fossils of Murrayglossus hacketti were discovered in Mammoth Cave, Western Australia, and excavated in 1909.

The specific epithet hacketti honours John Winthrop Hackett, "as a slight acknowledgement of his generous support which alone rendered the exploration of these caves possible.".

[5] Aboriginal rock art found in Arnhem Land in the Northern Territory may represent M. hacketti or the extant western long-beaked echidna (Zaglossus bruijni).