by repulsewarrior » Sat Jan 19, 2013 6:01 pm
...given, "on earth", is a clue, i can only hypothesise:
-one notes that the edge of each circular pattern is not perfectly smooth, implying a material surface.
-given that photos are often taken in lighting conditions which are not suitable for the object's description as an image per se, the diffuse quality of the light, in this image, and its colour temperature, creates illusions (i had a few myself) for other descriptive possibilities (which i am sure will follow from the other Forum Members).
...in my opinion it is a typical Diffuser, which one might find in the ceiling of an office, a finishing between the ventilation system and the ceiling system itself. unless you're looking for humour, of course, hope this is helpful.