Brain

Brains
Zombies actually eat brains. These "brains" in-game can be seen in one mini-game and alot of them seen in puzzle, I, Zombie and the rest of the series.

I, Zombie
Is a puzzle in Plants vs. Zombies. At starts, you get only a few zombies.

Few references

 * 1) http://[http://www.plantsvszombies.com www.plantsvszombies.com/]
 * 2) http://www.popcap.com/
 * 3) http://www.wikipedia.com/
 * 4) http://www.wikitionary.com/