Food of the future!

X is a 1973 American sci-fi film directed by Richard Fleischer. It is set in a dystopian future. Much of the population survives on processed rations including X, which, advertised as being produced from "high-energy plankton" turns out to be processed human meat. Identify X.

ID this planet

X was a small planet proposed to exist in an orbit between Mercury and the Sun. It was hypothesized to explain the peculiarities of Mercury's orbit in the 19th century.

It also happens to share it's name with another planet, one out of science fiction in a famous sci-fi franchise across TV and films. Home to an extraterrestrial humanoid species noted for their attempt to live by logic and reason with no interference from emotion.