Watching harvester ants (Messor andrei) on a serpentine rock, covered in colorful lichen. At the end, some much smaller harvester ants (Pheidole californica) -- and a spinning insect seen in the grassland nearby. See "People" for images of Paul Heiple and his companion, at this spot.
I followed one ant in particular. She was struggling with a long seed. In nine minutes, she bumbled back and forth, never giving up, yet making little progress. Other ants came by and communicated, then left her to her task. Finally she wandered off the serpentine rock and into the grasses. I don't know if she made it to the nest. This reminded me of evolution: random and messy in detail, but capable of leading to interesting results over long time periods and many tries. I guess there are some seeds that are easy to carry, some that are too large or clumsy for one ant, and some that are on the bubble -- like this one. If an individual worker ant just keeps on trying, she may or may not reach the nest with her find. In the long term, the nest will benefit.
For the lack of coordination and goal-seeking when several ants try to move an obstruction, see the 4/22/2015 collection nearby, also in "Adventures on a Smaller Scale".