|Pilobolus is also known as the shotgun fungus due to its interesting reproductive habits|
Pilobolus is a personal favorite fungus of mine, due to how interesting its life cycle is. This fungus grows on the dung of herbivorous animals. However, that's not the interesting part. It begins with the fact that the spores don't land on the dung after it's deposited: they're there before it ever touches the ground. How does it get there? The animal eats grass that has already been contaminated by the spores. This way, the spores reach the dung when it's still incredibly fresh.
One of the major difficulties in this, though, is that animals generally won't eat vegetation that is close to where dung has been deposited, something called the "zone of repugnance." This makes sense for the animal, and creates a problem for the fungus. So, how does it get past this problem? Pilobolus actually shoots its spores through the air to try and reach fresh grass. The sporangium (or bunch of spores) develops on top of a high-pressure, liquid filled section. When the spores are mature, this section burst and the sporangium is shot away. Considering how small these structures, it's remarkable that the sporangium can go as far as two meters.
Below is some brilliant footage of this fungus in action:
Interestingly enough, certain nematode worms that are internal parasites to the same herbivores will often hitch a ride on the sporangium. This can actually be seen in the video above. Look for small white thread-looking things during the closeups of the fungus. Those are the worms.
Sources are Utah State University, University of Wisconsin, Cornell University, and the BBC. Image is from Flickr.com under a Creative Commons license.