Peas and Sweet Corn

I was making cottage pie for supper tonight (it was yummy) and I made some veg to go with it. I was boiling the frozen pea-and-sweet corn mix, when I noticed that the peas and corn seemed to separate into pea regions and corn regions. So I thought maybe they just came out of the packet in frozen pea clumps and frozen corn clumps... So I swished the peas and corn around a few times in the pot and true's bob, every time they soon separated into pea regions and corn regions again. Bizarre. My theory version 1.0 is that the corn is lighter than the peas, so it gets caught in the currents in the boiling water and ends up together.