There have been Chimpanzees observed taking part in some rather bizarre behavior. Chimps native to Guinea Bissau, The Ivory Coast, and Liberia have been storing a good number of rocks in the hollows of trees. Then, typically a male chimp, picks up one of the rocks, walks a short distance away, makes some sort of grunt that resembles prayer, and hurls the rock back at the tree, leaving a mark. Then the rock is picked back up and put back into the tree to be reused in the same manner.
A team of 80 international scientists, led by Hjalmar S. Kuhl and Ammie K. Kalan, have been conducting the study. They set up camera traps in 4 different locations, where they were able to capture footage of chimps taking part in this unexplained behavior.
No Chimps east of these countries have been observed doing this. What is even more strange is that there does not seem to be any reasoning behind it. There is no tie to survival, acquiring food, mating, or furthering ones status. Many researchers are saying that it may be a unique display of power, marking one’s territory, or even a spiritual ritual.