Fuuuuuuuck. Cordyceps Fungi!

My balls just shrank up inside my torso after viewing an image of this superbeast. Fungus that replaces the host's tissue? That's some "desolation of space" type horror that I surely won't be able to shake from my dreams for months. Check it: 

Cordyceps fungi invades its hosts (mainly arthropods), and eventually replaces the host’s tissue with its own parasitic tissue. Once the arthropod is dead, cylindrical or branching growths emerge from the creature’s dead body. These “fruiting bodies” that sprout out of the dead arthropod then spew out more spores to infect a new host. Some species also have mind-control capabilities, convincing the host to travel to a place where the fungus will find optimal growth conditions before the host dies.

Thanks for the hot tip Hilldawg.