Chameleons

Chameleons are reptiles that are very large in size. In the anime a chameleon was the personal summon of the lord of Neck Country. Also both of Nagato's Animal Paths were capable of summoning a giant chameleon that possessed Rinnegan eyes and had multiple piercings.

Abilities
Chameleons possess the ability to blend in with their surroundings which make them practically invisible, allowing them to catch their enemies off guard. They can also walk on vertical and inclined surfaces, like walls. Chameleons also possesses long tongues which they use to grab a hold of prey and can be used in battle to restrict an opponent's moves.

Trivia

 * In the manga, Nagato's chameleon is seen with chapter 374, the snake but had regular eyes. This was later corrected in subsequent chapters and the snake was seen with Rinnegan eyes.
 * The same error was made in chapters 550 and 551.