Injectors

"Injectors" as referred to by Peridot, appeared in "On the Run", scattered all over the Kindergarten. They currently appear to be in a state of disrepair.

Appearance
The Injector machines resemble bacteriophages, which are viruses that infect and reproduce within bacterium, sometimes destroying the bacterium. The bottom of the machines have one large drill, surrounded by smaller ones. Their upper structures sport large, red, gem-like ornaments on the top.

The body of the rig itself seems to showcase a clear panel containing within it what appears to be either an organic heart, much like the Crystal Heart located in the center of the Crystal Temple, or an artificial womb. These seemingly organic hearts/wombs are attached to the head and feet of the machine via red and blue tubes that resemble arteries and veins, respectively. Due to this, these machines can be considered bio-mechanical.

Function
As revealed in "Keeping it Together", Injectors drill into the ground, injecting a Gem deep underground. The implanted Gem then drains the life-force from its surroundings in order to form a gemstone and eventually be "born" from it.

Trivia

 * In "On the Run", Amethyst refers to these as "Old Gem Junk".
 * Injectors possess the ability to climb walls at 90 degree angles.
 * It is stated by Garnet that if the Kindergarten is reactivated, the Injectors would power back on and continue the project.
 * Pearl was able to knock an injector over by throwing her spear at it.
 * Their official name was confirmed in the episode "Keeping it Together", however injectors were previously mentioned during Peridot's diagnostic log in "Marble Madness".