Tar pits are locations of deep pools of sticky black tar. Fictional tar pits may feature the bones of great beasts sticking out from them, ruins from another age slowly being consumed, or recent wreckages with people desperate to escape before it becomes too late. Extensive tar pits may act as impassable areas (and as such may form a naturally occurring border) or have hidden trails that run through them. They may be home to fossils or archeological dig sites. In game worlds, tar pits may serve as a type of terrain hazard or obstacle.