Code point
U+228F
Glyph appearance depends on your fonts.
U+228F
SmU+228F SQUARE IMAGE OF is a Unicode 16.0.0 character in the Math Symbol category. It belongs to the Mathematical Operators block.
Choose the representation you need, then copy its value.
U+228F
8847
⊏
⊏
⊏
E2 8A 8F
228F
0000228F
%E2%8A%8F
\u228F
\u228F
\u228F
\228F