Tooth Fairy
The Tooth Fairy was a mythical creature in Earth culture which, according to legend, collected "baby teeth" lost by young children during the night, leaving coins or other gifts in their place. Among adults, the Tooth Fairy was used as an example of a foolish belief.
The Tooth Fairy retained prominence in Earth culture into the 23rd and 24th centuries. (TOS novel: Vulcan!; SCE eBook: Lost Time)