Spider-tailed Horned Viper (Pseudocerastes urarachnoides)
…a species of Persian horned viper collected in western Iran in 2006. Like its common name suggests this unique viper has an odd wind scorpion shaped growth at the tip of its tail. Originally it was thought to be a Persian Horned Viper (Pseudocerastes persicus) with a odd tumor, but it was later reveled that a whole population had these growths and they were named a new species.
The growth is actually used as a lure and experiments have shown that birds who peck at it were lead to the vipers head and eaten. So far it has only been observed preying on birds but it is though to prey on other predators of wind scorpions as well.
Images: Omid Mozaffari and Fathina et al.