A rare rhino rat snake (Rhynchophis boulengeri) emerges from its shell at ZSL London Zoo. This is the first time these so-called “green unicorns”, from the mountains of Vietnam, have been bred in a European Zoo. The Reptile House produced a clutch of eight snakes. They grow to a metre long.
Source: BBC News – Science & Environment
Mapping the Marvellous 
Does the fact that you’re referring to this breed of snake as rare also mean it’s endangered as well?
To my knowledge it’s not classified as endangered according to the Red List, but the breeding was part of an international captive breeding programme, so it must be rare enough to depend on conservation.
Hey thanks for answering that question — (since I was too lazy to check into it myself)
Ah, thanks to google… ;-)