I have a question that I wonder where to ask. It's about two stories that share an element, and I want to know if the writers independently invented it, which seems quite possible, or the later one was inspired by the earlier one. I have a question like that on Sci Fi at
scifi.stackexchange.com/q/242351/4918 , as well as an answer at
scifi.stackexchange.com/q/242351/4918 .