Code point
U+25A7
Glyph appearance depends on your fonts.
U+25A7
SoU+25A7 SQUARE WITH UPPER LEFT TO LOWER RIGHT FILL is a Unicode 16.0.0 character in the Other Symbol category. It belongs to the Geometric Shapes block.
Choose the representation you need, then copy its value.
U+25A7
9639
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E2 96 A7
25A7
000025A7
%E2%96%A7
\u25A7
\u25A7
\u25A7
\25A7