This particular fungi is not all that uncommon, though the way that it infects insects is rather disturbing. For every insect species, there is a specific cordyceps fungi, it is natures way of keeping things from getting the upper hand over one another.
Here an infected ant has the spore bearing stroma arising from just behind the head. It takes only one very tiny spore to infect the ant and the fungi consumes the ant from the inside out.
Cordyceps fungi is so powerful that it can completely wipe out an entire colony of ants.