The coat of arms shows the nopal growing from a small island or rock in water. This refers to Lake Texcoco, the lake where the Mexica founded Tenochtitlan. Mexico City later grew in the same basin, over and around the old lake environment.

For learners, this detail matters because the flag is not only about abstract values like hope or unity. It points to a specific place and origin story: the foundation of Tenochtitlan on an island in Lake Texcoco. That image connects the flag to the geography and history of central Mexico.