The Recapitulation Theory
The "Embryonic recapitulation" theory was disproved decades ago, yet some uninformed people are unaware it has been debunked and are still teaching it. This theory says that the human fetus goes through various evolutionary stages in the mother's womb. Some people wrongly believe that the human fetus in its early stages has "gill slits" like a fish and a "tail" like a monkey. This is supposed proof that humans show signs of going through the evolutionary process of development.
However the "gill slits" are folds, or wrinkles. In fish, the gills are designed for water to flow through to extract oxygen from the water. However, these folds in humans develop into the tonsils, ear canals, parathyroid and thymus glands. They only appear to be gill slits. Only a prejudiced mind would call them gills because they look like fish gills.
The "tail" isn't a tail but the end of the spine. The tip end is called the coccyx and sticks out because it is the first to develop.
Although evolutionists no longer accept the recapitulation theory, many people at one time believed this was proof for evolution. Even today some people promote this theory, not realizing it was disproved long ago.