Fire ants use their bodies to construct Eiffel Tower-looking structures when they run into a tall obstruction while looking for food or escaping to new areas. A new study from the Georgia Institute of Technology suggests that they build these structures without a leader or coordinated effort. Each ant wanders around aimlessly, adhering to a certain set of rules, until it unknowingly participates in the construction of a tower several inches tall.
Source: http://www.news.gatech.edu/2017/07/11/ants-build-sinking-eiffel-towers-when-trying-escape