This is a square, which is black. This emoticon can be used to represent all kinds of black and square things, such as blackboard, black box, computer display screen, black bag, black marble tiles, and so on.
Different platforms depict different square patterns. The squares depicted on most platforms have four right angles, but in the emoji of Facebook platform, the four corners of the squares have a certain radian, which makes them look relatively smooth. In addition, the square depicted by emojidex platform has a strong stereoscopic impression, showing the shadow part of the figure. Different from others, the au by KDDI platform depicts a green square, and two white lines and a small white dot are added in the upper right corner to represent the luster of the graphic display. As for LG and HTC platforms, white and gray squares are depicted.