A cluster of buildings appeared suddenly near Guanyin Mountain in Xiamen on Feb. 19. Local office workers were surprised by the scenery, and regarded it as a kind of mirage. One woman surnamed Zhou said that the buildings appeared on the sea as the sky darkened. Another office worker noted that the spectacle lasted for roughly an hour. 

The mirage was an optical phenomenon caused by specific conditions of humidity, light, temperature and wind. It normally appears along coastlines and in the desert.