"They are. But do you know what forms them?" He's being very mysterious, and he knows it. But he only pauses briefly, enough time to get a yes or no from Joji, before continuing.

"A properly-formed Greeed can create what's called a Yummy. A creature based off of a human's powerful desire. It goes out into the world and indulges that desire, building up Cell Medals all the while. When it's torn apart? The Cell Medals are released, free for the taking."