TIL a diaphragm is a method of birth control, which involves blocking the cervix and the use of spermicide. It must be left inside upto 8 hours after sex

https://en.wikipedia.org/wiki/Diaphragm_(birth_control)

https://www.reddit.com/r/todayilearned/comments/156dgok/til_a_diaphragm_is_a_method_of_birth_control/