Researchers have finally discovered why wombats' faeces is cube shaped, and won a prize for their efforts.

When a group of University of Tasmania researchers sliced open a wombat corpse, they were surprised.

For years, scientists had believed the cubes were formed "at the point of exit".

But this more recent discovery revealed that the unusual shape has more to do with the animals' intestines.

Senior lecturer in wildlife ecology Scott Carver was dissecting wombats to study mange disease when he and his research team made the discovery.

"It was quite incredible," Dr Carver said.

He and his colleagues presented their work at a physics conference last year and have now been awarded an Ig Nobel prize — an international award for research that makes people both laugh and think.

"We found that their cubed faeces actually goes back about a metre inside their intestines from their anus, which is really quite far inside their bodies," Dr Carver said.

Using a microscope, the team discovered regular variations in the muscle thickness around the circumference of wombats' colons.

"That probably sharpens the corners of the faeces as it descends down their intestines," he said.

Wombats intestines are said to be nine metres in length — a size Dr Carver described as "just huge" given the size of the animal compared to the average human.

The researchers found wombats' intestines created the unusual shape of their faeces. ( Supplied: University of Tasmania )

"Grass takes about a week to get through a wombat's intestine whereas our intestine is about two thirds the length that of a wombat, and it takes us about 48 hours," he said.

He said wombat scat was also much drier than human faeces.

The square-shaped scat has long baffled bushwalkers and scientists.

Dr Carver said the discovery dispelled many myths, including that wombats' pubic bones squeeze their faeces into square packages, that the animals had a square-shaped sphincter and — his personal favourite — that the animals defecate and then pat the scat into shape.

He said not only was the shape of wombat faeces unique in the animal kingdom, it was also "deposited in prominent place to communicate with each other".

The Ig Nobel prizes have been awarded since 1991, with only 10 awards handed out annually from a pool of about 9,000 nominees.

Other winners this year included the invention of a nappy-changing machine and a study that compared how well paper money from different countries can transmit dangerous bacteria.

Dr Carver accepted the award at Harvard University in Massachusetts on behalf of his team.

"It's a comical and tremendous honour to receive one of these awards," he said.