Here's how Brains explains about the Seed goes in Ed, Edd, n Eddy's Ed-ventures of Transformers: Age of Extinction.
Joshua: You CIA guys are really subtle. What a deft hand. I'm sure nobody noticed all that. Look. In a few minutes, there are gonna be feds all over this place, and I don't want them finding our Holy Grail. So we're gonna take all our R&D, we're moving it to our China Facility. Yeah. I want you to bring me the Seed, but I want you to bring it to me there.
Su Yueming: Mr. Joshua I would not describe your product testing as perfected.
Joshua: We have plenty of time for improvements in China.
Gill: Sir, Galvatron. He was...
Joshua: A fiasco. A farrago. An embarrassment. And he spoke How did that happen? Do you know what a flaw is, Wembley? A flaw? A flaw is a total failure. I did not have control over my prototype, and I want to know, WHY!
[we see Bumblebee driving up to the train museum]
Crosshairs: Lets give Bumblebee the good news. We've got a ship now, we're leaving.
Optimus: You humans. After all we have done. You don't know what you've brought upon yourselves.
Cade: What? What is it now? What re you talking about? I mean, I'm doing stuff out of my league here!
Optimus: You don't see who's controlling who. Within that man made prototype I fought, I sensed the presence of Megatron.
Cade: What, the Decepticon who started the Chicago War?
Edd: No, that was Sentinel Prime.
Brians: How do you think KSI built those bots in the first place, hmm? they had a whole mess of dead Decepticon heads and they were downloading their minds! And I was in charge of autospy duty. No union, no benefits, no nothing. They hooked me up to Megatron, and that mind isn't as dead as they thought. He fed them the science and specs! All so they could build him a brand-new body. Then, he inflected it with his evil, nasty chromosomes. They had red, beady eyes. [exhales] They got all in my lovely locks. Oh, I can smell it right now! Total inside custom job! KSI may have named the body, the snappy name Galvatron, but that's just Megatron reincarnated!
Scootaloo: So, Galvatron is Megatron this whole entire time!
Rigby: And now he's got a new army! A bigger one!
Tessa: You knew this, and you didn't warn them?
Brains: Little girl, you can go to a pretty dark place when you on death row. He's been play KSI all this time, all so that he could manipulate them into going after the Seed.
Shane: Wait. the Seed?
Tessa: Those nasty soldier that were chasing us. I saw them board the ship, and they took something that they called the Seed.
Hound: Listen. Sixty million years ago, given or take and eon?
Optimus: Thousands of planets were' cyberformed with Seeds.
[The flashback plays with the little dinosaur seen from the beginning]
Optimus: They turned your organic life into our elemental menials. Our creators destroyed your world. To make us.
Brians: And that's what Galvatron wants to happen again. He wants to detonate that Seed in the biggest city and kill millions. He's gonna show the world, "Baby I'm back!".
Optimus: The blast wave will incinerate that city into molten metal. He'll have enough to build a massive army. And annihilate your species forever.
Brains: You dumb, greedy stupid heads, just brought extinction to yourself. Not my problem though. I'm free at last. Whole thing worked out good for me. I'm walking.
Cade: We gotta get the Seed before Galvatron does.
[We see China, Joyce and Galvatron unloaded]
Joshua: The Seed is going to be the salvation of our company. We take delivery tonight. And next month, we detonate safely in the Mongolian Desert. And we’ll create enough Transformium. For a hundred years.