© William Robichaud/WWF
The saola looks like an antelope. It's characterized by two parallel horns that can measure up to 20 inches long.
The animal is so rare that is has been dubbed the "Asian Unicorn."
"When our team first looked at the photos we couldn't believe our eyes," Dr. Van Ngoc Thinh, WWF-Vietnam's Country Director, said in a statement. "Saola are the holy grail for South-east Asian conservationists so there was a lot of excitement."
The saola was first discovered in 1992 in Vietnam near its border with Laos when a survey team from the WWF and Vietnam's forest agency found a skull with unusual horns in a hunter's home. This was the first new large mammal discovered in more than 50 years, according to the WWF.
WWF
Since the saola is hardly ever seen, very little known is about its behavior or even how many are out in the wild. Experts believe that no more than a few hundred exist.
The saola is listed as critically endangered on the IUCN Red List. The animal faces threats from hunting - they may be caught in snares to catch animals like deer for the illegal wildlife trade - and loss of habitat from road construction.
The most recent saola sighting gives conservationists a better idea of their range and will help with protection efforts.
Here's a video of the elusive saola: