Later Morin discovered the Morin surface and used it to construct other sphere eversions. Kusner conceived the minimax eversions in the early 1980s&colon; historical details. In particular, this means that sphere eversions exist, i.e. one can turn the 2-sphere "inside-out". Eversions via half-way models are called "tobacco-pouch eversions" by Francis and Morin. In geometry, minimax eversions are a class of sphere eversions, constructed by using half-way models.