Good day, Matthias.
Your photos have confirmed what I assumed. Yes, the needle that mounts your M55 is an N75EJ. I put some comparative images, in this case with my Shure M44 (same body as the M55 and fully compatible needles) with an N44-7
First of all, you can see the differences in both the insertion angle on the cartridge and the positioning of the stylus on the record.
In these others, you will see the different shape of the needle (another fact: except for 78rpm, there is no green needle for the M55 and M44 cartridges)
Finally, here are pictures of those needles, in this order: N75EJ (yours), N55E, N44-7 and N44-3 (for 78rpm records):
Your N75EJ stylus appears to have been carefully curved by expert hands so that it is at the correct angle on the record
I don't doubt that the needle inserts into the cartridge, nor that the sound is good, I was just surprised to see that N75EJ stylus in that cartridge.
Like I said, if you like it that's fine. Enjoy it.
Best regards.
Juan