Black Lower Left Triangle

The Black Lower Left Triangle at U+25E3 is a filled geometric symbol shaped as the lower-left half of a square divided diagonally. It sits in the Geometric Shapes block and is used when a compact triangular block or directional corner marker is needed rather than a mathematical operator. Its most common appearances are in charts, diagrams, interface mockups, and decorative layouts, where it can mark a lower-left corner, indicate a diagonal fill pattern, or serve as one tile in a four-triangle set. Designers may pair it with the other black corner triangles to build simple mosaic patterns, quadrant indicators, or legend keys showing which half of a cell is shaded. It also turns up in plain-text art, terminal-style graphics, and social media decoration because it gives a solid diagonal shape without requiring an image. In data tables or annotations, ◣ may be used informally to suggest “bottom-left,” but that meaning is conventional rather than standardized, so it should not be treated as a universal navigation symbol.