When archaeologists lifted the lid on an Egyptian coffin that had been stored at Sydney University for 150 years, they got an enormous surprise.

They had no idea the 2,500-year-old coffin was filled with human remains.

Researchers are now using the latest scientific technology to piece together an ancient mystery.

"We are about to start a really detailed project to scientifically investigate these remains in the coffin and ask a whole bunch of questions, but really, 'Who is inside the coffin?'" investigation lead Dr Jamie Fraser said.

The mummy's feet are wrapped in this bundle. ( ABC News: Natalia Morawski )

The mummy is not whole and the remains have been heavily disturbed.

"A tomb robber has probably come in and rooted all the way through trying to find jewels and amulets," Dr Fraser said.

Hieroglyphics on the coffin show it was made for a priestess called Mer-Neith-it-es, but coffins don't always hold the remains they were intended for.

Often the mummies are discarded from their original coffin, although Egyptian antiquity sellers would put another mummy inside if a customer requested it.

'They're the remains of an adult of 30-plus'

As part of the effort to find out everything about the mystery mummy, the coffin and its contents were laser scanned to create 3D models, and then sent for a detailed CT scan.

Radiologist Professor John Magnussen said despite the remains being disturbed, there are still enough clues to solve part of the mystery.

"It's older, and it's got some early degenerative changes and the sacrum is fused, so we know it's definitely an adult," he said.

This was important news for the archaeologists.

"We know that Mer-Neith-it-es herself, this priestess for whom this coffin was made, was an adult," Dr Fraser said.

"And the joins in those bones say, yeah, they're the remains of an adult, and actually they're the remains of an adult of 30-plus."

The CT scan showing the mummy's toes (left) ( ABC News )

The scan also revealed that the feet and ankle bones were largely intact.

After the scan, Egyptologist Connie Lord was responsible for sifting through layers of debris to find the feet of the mummy.

"There could even be toenails which would be thrilling — that's what I want," she said.

"The toenails are fantastic for radiocarbon dating."

'It's just an incredible find'

Scientists inspect the black lump of resin that was once inside the mummy's head. ( ABC News: Natalia Morawski )

During the physical examination, Dr Lord made another important discovery — the resin poured into the mummy's skull after its brain was removed.

She said the cast is similar to one found inside a coffin of one of the most famous mummies ever discovered, Tutankhamun.

"It could tell us so much," Dr Lord said.

"It's just an incredible find, I don't remember anyone finding something like this.

"It would have to be incredibly rare."

Mer-Neith-it-es being scanned and showing on the computer screen. ( ABC News )

These days it's very unusual for a mummy to be excavated because it's considered unethical to disturb human remains.

But the artefacts inside this coffin are in desperate need of preservation.

"Little by little this excavation is really telling us more about the person in the coffin and hopefully give it some dignity that it lost when in ancient times it was looted so badly," Dr Lord said.

It will take months or years of further analysis to definitely identify the remains.

In the meantime, Mer-Neith-it-es' coffin, along with three others owned by the Nicholson Museum, will be exhibited in a new museum on the university grounds, along with a display showing the work done by the team to try to discover who is inside the mysterious coffin.