?We can?t save everybody?: could biobanking offer Australian animals a last hope against extinction?

On 15 December 2014, inside a repurposed shipping container in the Atlanta Botanical Garden in the USA, Mark Mandica heard an unfamiliar animal call.

It was a reddish-brown frog about the size of a peach, called Toughie. He had lived silently for nine years since arriving from Panama - where the highly infectious chytrid fungus disease had arrived, leaving swathes of dead frogs in its wake.

He was believed to be the last Rabbs' fringe-limbed tree frog in the world.

"Then it struck me that this frog was still vital and sounded very strong, and was singing out for a mate that would never come."

When Toughie's heart stopped on 26 September 2016, the species died out. The next morning, across the country in San Diego, amphibian expert Natalie Calatayud was presented with Toughie's testicles.

This strange gift was part of a plan to use "biobanking" for conservation. The idea of freezing biological material is not new, having been used in medical research and livestock breeding programs for decades. But by using liquid nitrogen to lower animal tissues to -196C, where almost all processes of life within a cell halt, scientists hope to buy more time for assisted reproduction to help a captive colony, to investigate a devastating disease, or preserve DNA for cloning.

Toughie now exists as 16 vials of precious mush, awaiting a time when technology - and potentially an unknown surviving mate - allows for the revival of the lost species.