Spider-tailed horned viper (Pseudocerastes urarachnoides), also known as Persian viper, is a species of viper endemic to Iran. It was discovered/described in 2006, and what makes it interesting is its tail, which has evolved to look like a spider.
The snake uses its tail to lure animals that eat the insects within the attack range. Then it strikes from its rocky camouflage bringing death to the unsuspecting animal.
This is not the only animal which uses so called feeding mimicry to attract prey. The behavior is seen in a number of snakes and couple of lizard species, but is also seen with some fish species. However, it is mostly used by snakes (predominately vipers), but the Persian viper seems to be the most bizarre with its spider-tail.