Davis replied and told me that I might have a faulty segment, which I don't.
Another technician said that he had seen that before, but never growing at this rate.
It keeps growing by the day.
But if you look at the display at a certain angle with a light source at the other side,
you can see that the thingy is immediately underneath the top glass and not on
the LCD.
So the fungus (or alien life form..) assumption might hold some water.
Greek Helios loves to destroy fungi, bacteria and viruses,
so I think I will leave the LCD outside under the sun for a few hours
and see if the growth stops.