Some Slinky toys are star-shaped (1st picture), like my daughter's one. Then, when extending them , it forms a periodic pattern: a non-linear wave!
It could be helpful to teach what is a nonlinear-wave or signal to students. The star-shape may be related to the dynamical phase-space of this...
thank you for the link, very interesting this concept of 'sub-pixels' with rectangular shape. I wonder why all TVs have the sub-pixels stacked horizontally and not vertically? Probably just a convention
I observed a strange optical phenomenon when lighting a candle in front of a tv screen, in the dark (attached picture). There seems to be two lines forming an 'X' figure with a colored pattern (of diffraction, I suppose). I think it must be related to the material structure of the TV screen...