Black Receiver

Nagato implanted chakra receivers into each of his Six Paths of Pain as body piercings. Doing so allowed him to transmit his chakra into the bodies and control them remotely as if they were his own. The many animals summoned by the Animal Path also had a number of these body piercings, suggesting that Nagato controlled them as well. These receivers seem to be incredibly durable, as seen when Shizune was performing an autopsy on the first Animal Path and many scalpel were broken when sawing them off the body. The Summoning: Demonic Statue of the Outer Path, when used, pierced many chakra receivers through Nagato's back which in turn allowed Nagato to control the statue.

Trivia

 * Nagato has also used modified versions of these receivers to act as blades, allowing him to disrupt his opponents' chakra flow by transmitting his own chakra into their bodies when pierced.