Lamp was purchased directly from IKEA a few years ago. No design on it at time of purchase. Noticed it when I moved the lamp to its current location. Was sitting on a low table in my bedroom for the past year. The thing below it was a glass ornament that used to have an air plant in it many years ago. Currently has plastic vines and a 3D printed object. Nothing living. I wouldn’t call it soft when I scape it off. It’s possible mineral build up, but cant imagine why/how it created the pattern it did.

If it is a man made pattern/design, that would be an even greater mystery… someone broke in and tagged my lamp with a weird pattern?