Rolling and wheels in the natural world
A kind of organism called archaea, which are different from bacteria, also use flagella powered by rotating motor proteins. The two kinds of flagella evolved from different parts. Eukaryotic cells are a more complex kind of cell found in plants and animals. Some of these cells also have flagella called cilia, but these flagella do not rotate at the bottom. Instead, they bend so that the tip of the flagella moves in a circle.