They can live for more than a century, seem to be able to keep menopause at bay and may hold the key to anti-ageing - if they don't die out first.
Researchers believe Australia's freshwater turtles, one of the most threatened groups of animals on the planet, could provide an insight into the biological process of growing old.
Freshwater turtle expert Dr Ricky Spencer of the University of Western Sydney says the oldest turtles produce the most eggs.
"There's no sign of menopause so they're defying the common-held view that cell death is inevitable," Dr Spencer said.
"These guys are either delaying that, or they don't expire like any other vertebrate."