Check out the above video for an amazing examples of what can happen when a group of ants gets separated from their colony. Apparently these are sometimes described as "Ant Vortexes" and are the product of a sort of infinite loop of ants that follow one another's scent.
For those of you who aren't up on your "ant physiology," it is common for colonies of ants to communicate with one another via chemicals that they excrete as they travel. This ultimately creates a kind of natural pathway that other ants will automatically follow. The ants have different kinds of chemicals to convey different kinds of information, such as food, predators, or general navigation.
However, when you have the blind following the blind, you open yourself to the possibility for situations such as these. Since there is no one ant that directs the spiral, there is almost no way to stop the behavior from happening, aside from outside intervention, and the ants continue to spiral until they are exhausted.
I think it's a pretty amazing example of a pretty powerful effect that arises out of relatively simple units and rules that those units follow. It reminds of me of the number of pathological conditions in the brain, and how they are often the product of a similar simple-to-complex mechanism.