Cordyceps — or “Zombie Fungus” — are a parasitic fungus that thrive in hot, humid climates like tropical forests. There are thousands of different types of cordyceps and each targets a specific species of insect to infect.
Spores from this killer fungus infect the insect’s brain, and, later, the fruiting body of the cordyceps will erupt from that insect’s head and body. When it’s finished growing, cordycep spores burst from the fungus and infect any insect of the same species unlucky enough to be nearby.
While these killer fungi sound like they're straight out of a horror movie, they do have an overall positive impact on their environment because they keep insect populations from growing out of control. Plus, they have no effect on humans, so don't worry: