Lateralis 

Based off of the cordyceps fungus in real life and from the game The Last of us, they are a single corpse controlled by a hivemind fungus.

The fungus communicates with each other to move and control the corpse, being able to communicate and see through other fungus under the same family, it cannot infect anyone else counter to cultural belief.

The human body's immune system is strong enough to fight it off, a dying corpse on the other hand? different story.