Cu Rua was no ordinary turtle.

For starters the male was huge, about 200 kg in weight. He was also revered. The Vietnamese consider four animals sacred – the dragon, the phoenix, the unicorn and a mythical turtle who in the 15th century, kept the magical sword which was used by the Dragon King to fight against Vietnam's then Chinese oppressors. Rua was believed to be the incarnation of that turtle, attracting visitors from around the county to the lake in Hanoi where he lived. Last week, Rua was found dead, floating in the same lake.

There was one more reason Rua was unique: His death leaves only three more Yangtze giant soft-shell turtles on this planet. And despite concerted efforts from conservationists to breed these critically endangered animals, the chances of preventing their extinction seems more and more unlikely.

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Yangtze giant soft-shell turtles were once a little more common across China and Vietnam. But habitat-loss, pollution and the harvesting of the massive animals brought them down to their current status, with just three remaining.

One is a turtle of unknown gender in a lake just outside Hanoi, according to Scientific American, and the other two are a male-female pair in China. Researchers have been trying for years now to get the Chinese pair to mate, but none of the eggs that emerged from the breeding ended up hatching. Conservationists even attempted artificial insemination, but the eggs that came from that experiment were infertile.

Researchers believe the Chinese male might be infertile, which is why the efforts haven't been working. That means one of the few remaining options is attempting to gauge the gender of the remaining Vietnamese turtle and, if male, trying to get him to mate with the Chinese female.

But as the New York Times reports, doing so would mean bilateral collaboration, especially over an animal that is taken as a Vietnamese symbol for resistance against the Chinese, which makes things that much more complicated.

Rua, meanwhile, will be embalmed, allowing those who still consider the animal sacred – or want to see what a likely-to-be-extinct animal once looked like – a glimpse of the Yangtze giant soft-shell turtle.