That mysterious 01
Some time ago, we learned the story of that mysterious J. There is another mystery character that sometimes shows up in place of a smiley face: the \001.
The character starts out as the Unicode U+263A, which looks like this: ☺. In code page 437, this character lives at position 1, and depending on what program is being used to display the character, it might appear as a box (representing the character U+0001) or as the escape sequence \001.
You can think of this as a version of the mysterious J, but taking a route through code page 437, or you can think of it as how a bullet turns into a beep taken in reverse, then reversed again.