Mega seeds appear in the pilot episode. They are found inside the fruit of the Mega Trees in Dimension 35-C. Rick claims they have certain properties which make them extremely useful to his research. Rick says he has smuggled them through inter-dimensional customs several times before.
Mega seeds are large, brown, and teardrop-shaped. While Rick doesn't disclose all of the properties of these seeds, it is likely they are considered contraband material, as he needs Morty to hide them in his rectum to try to sneak them through interdimensional customs.
Their only known property is the ability to endow a person with super-intelligence, a trait which Rick uses to manipulate Beth and Jerry into thinking he is helping Morty tap into his hidden genius. After a short period of time, the super-intelligence wears off and the seed instead causes loss of motor and brain function for several days.
- ↑ "and [the seeds]'ll fall right out of mine; I've done this too many times Morty." -Rick talking about sneaking Mega seeds through customs in pilot episode.