The vaginal corona is an antatomical feature consisting of thin folds of mucous tissue located 1-2 centimeters inside of the vagina. The thickness and appearance of the vaginal corona varies from body to body. The vaginal corona has no known function. It is thought to most likely be a remnant of fetal development
Vaginal corona is a modern term for the hymen.
Kinkly explains Vaginal Corona
The Swedish Association for Sexuality Education proposed renaming the hymen to vaginal corona in 2009 as a means to dispel myths surrounding the hymen. Namely, that it is a seal on the vagina that is broken when a woman becomes sexually active. In fact, experts aren't exactly sure what purpose, if any, the vaginal corona plays.