[boobsbr]

The backspace key on my Lenovo keyboard is identical. And if I remember correctly, it was the same key on an electrical typewriter I used in the 90s.

[DanBC]

On typewriters you would backspace and then overtype an X. Those keyboards tend to just use the word "backspace" or a back arrow symbol.

So typewriters use this symbol when they automate the overstrike or they moved to correction tape.