Just a quick AI spit out...
In Greek mythology, the cube is primarily associated with the Problema Deliacum (the doubling of the cube), a famous geometric challenge that arose during a plague in Delos. According to legend, the oracle of Delphi instructed the Delians to double the volume of the altar of Apollo, which was shaped as a perfect cube, to stop the epidemic. This task proved impossible for the architects of the time without advanced geometric knowledge, leading Plato to use it as an allegory to criticize the Greeks for neglecting geometry and mathematics.
Additionally, the cube appears as a sacred symbol of Cybele (the Great Mother), whose name etymologically links to the Greek word for cube (kybe), reflecting her iconography as a towered goddess or a sacred stone/meteorite. In broader esoteric and later spiritual traditions, the Cube of Metatron is sometimes linked to sacred geometry, but this is not part of ancient Greek mythological texts.