Head jars

The technology to keep human heads alive in jars was invented by Ron Popeil, one of the many people now benefitting from his innovation. The jars, in conjunction with cloning techniques, can even store historical figures who had expired prior to the technology's debut. The liquid within the jar is, as one would expect, safe to drink and people have been shown to enjoy its flavour. This miraculous fluid, known as H2OGfat, is presumably sufficiently oxygenated and rich in nutrients. Heads can and do perform normal roles in society, including President of Earth, but most pass their days in quiet contemplation at the Head Museum. It is unclear which was developed first- the head jar, or cloning which recreates the memories of the deceased; however, if the former, Popeil's jars must have been invented in either the 20th or 21st Century. Head jars are one step away from the. The jars can also keep dog's heads alive as shown in

Main Functions
The full extent of the jars' functionality may never be known, however the jars are all capable of sustaining the life of one human's head. The heads are still able to eat and any waste is presumably filtered. The heads are able to survive out of their jars for an undefined period of time. Jars allow the inhabitant to control robotic limbs and bodies, while the jars themselves can contain attachments such as a pen to sign one's name. Jars are usually open at the top, though lids are available, but the liquid is able to remain within the jar while flying through space even when lidless. A black band is seen around the neck, but how it appears and what it does is unknown. In Bender's Big Score, Hermes' head is jarred, but the band spontaneously appears, and it disappears when Hermes' head is about to be put on top of his paradox duplicate body.

Key Appearances
The heads in jars appear in most of the episodes so this list includes the key appearances for them.
 * - first seen.
 * - inventor identified.
 * - first use of robotics.
 * - multiple head jars seen.
 * - rocket jar.
 * - survivability of freshly decapitated heads shown, liquid named.
 * - Matt's jar with built-in gun.
 * - time required to begin use shown to be less than a minute.