In this paper, we study a simple means for coordinating teams of simple agents. In particular, we study ant robots and how they can cover terrain once or repeatedly by leaving markings in the terrain, similar to what ants do. These markings can be sensed by all robots and allow them to cover terrain even if they do not communicate with each other except via the markings, do not have any kind of memory, do not know the terrain, cannot maintain maps of the terrain, nor plan complete paths. The robots do not even need to be localized, which completely eliminates solving difficult and time-consuming localization problems. In this paper, we use real-time heuristic search methods to implement ant robots and present a simulation study with several real-time heuristic search methods to study their properties for terrain coverage. Our experiments show that all of the realtime heuristic search methods robustly cover terrain even if the robots are moved without realizing this, some robots fail, ...