Lots of tiny mounds of earth, like minute molehills. Knocked the top of this one, found an ants nest. I spent over half an hour watching what they did. I know this because a runner asked me if I was alright, as I been lying down for over half an hour. 

They did not seem to be doing anything but run about to start with, but had started piling grains up before I left. I saw one black ant as well.