Primon

:"In physics, primon may also refer to the fundamental particle of the primon gas."

The BotCon 1999 story states a being named Primon as the first to hold the Matrix, and Prima the second. The story goes that Primon was killed by the Liege Maximo, and the Matrix ripped from his body. He is believed by some to have been the very first Cybertronian, before even Prima and was the first wielder of the Matrix, starting the long line of Primes.

While the story was penned by Simon Furman, it was never mentioned again in any other source.