This is a white square button, which is formed by superimposing two squares. This emoticon is commonly used in the switch button of power supply, and is used to control the opening and closing of power supply.
Different platforms depict different icons. Most platforms depict two squares with different colors, the big square is white and the small square is black. Emojidex, LG, Softbank, HTC and Docomo all depict one or two gray squares, and show different degrees of shadows, with small squares showing outward prominence or inward depression.
