Missing link may refer to: Biology. Missing link (human evolution), a non-scientific term typically referring to transitional fossils. Piltdown Man, a hoax in which bone fragments were presented as the "missing link" between ape and man. Geography. Missing Link, an unmapped system of underground partial-flooded caves that connects Mossdale Caverns in the Yorkshire Dales to the Black Keld. Art, entertainment, and media. Films. The Missing Links (film), a 1916 American silent crime film directed by Lloyd Ingraham.
https://en.wikipedia.org/wiki/Missing_Link