User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-184.77.255.73-20120518202823/@comment-3481504-20120519023010

...Well, but Eve didn't die in a season finale, but you're right.

Well, actually, Leviathans > Seraph does make sense, they (could) eat old Zach, but Dean already did.

But no, Archangels > Leviathans is how it goes.

however, Cas' comparesion to Earth with an aquarium, implicating them to the piranhas who eat everything, including the Angels, and Cas says that's one of the reasons God trapped them.