TIL: All the accidentals (b, #, ♮) are some form of b.
https://en.wikipedia.org/wiki/Accidental_(music)#History_of_notation
says:
the # sign and the ♮ sign in musical notation are derived from a square b.
In a Kiki and Bouba tangent, the round Bb was used to refer to the soft hexachord, the hexachordum molle (in German, minor keys are still called Moll) and the square one B♮ was used to refer to the hard hexachord, the hexachordum durum (in German, major keys are called Dur).