TIL that the Tetrahymena thermophila, a single-celled ciliated unicellular eukaryote, has 7 different sexes. Any two different sexes can mate and produce offspring, and the sex of the offspring can be any of the 7 different types. This allows for 21 different mating combinations.

https://www.nature.com/articles/nature.2013.12684
#til #todayilearned
https://www.reddit.com/r/todayilearned/comments/1g6lwln/til_that_the_tetrahymena_thermophila_a/