A 腐化的行尸 (Zombie Joe) is one of the different variants of Zombies. These zombies died and turned long ago, evidence of this being the fact that their bodies are highly decomposed.
These Zombies are normal zombies with not a whole lot of HP or strength, but like all zombies they can stun you and cause trouble in groups. The Festering zombie can spawn anywhere and usually is found in Day 7 hordes.
During night, the running behaviour is standard as all other zombies. If distance or sheer zombie numbers aren't a concern, scoring a head shot when it is running headfirst towards you can be slightly easier.
As of Alpha 17, Zombies can no longer be looted after a player kills them, however they do have a chance of spawning a loot container.