INSECTS: I just had a discussion about insect eyes with a man in the elevator. He tried to tell me that some insects have non-compound eyes, and he cited as an example the praying mantis. I told him that I was quite confident that all insects have compound eyes, but he remained unconvinced when I had to get off at the 3rd floor.
As it turns out, I appear to have been correct. Some insects don't have eyes, but the ones that do all have compound eyes. Take that, anonymous-man-in-elevator.