Della's Translucent Wall
This is a wall panel directly behind Della's desk. Here are some samples. Note the changes in Della's desk.

Picture 1 Episode 10. First season. An early apperance of the wall.

Picture 2 Episode 53. Second season. It glows in the dark.

Picture 3 Episode 144. Fifth season. What's that all about?

Picture 4 Episode165. Sixth season. Different leaves and desk.

[The Office][Perry Mason TV Series]