Many (not all) bacteria get around by means of a "outboard motor" which we call a "flagellum".
(see picture). It has 3 parts - a filament, a hook and a basal body (only my Biology class will be
expected to know this!). Darwin had no idea this existed by the way - nor did he know about any of the structures in the cell - it was a simple cell to him with no parts as far as he knew. There is nothing simple about a cell as we know today. The question - could this have evolved?
(Going to Youtube you get a lot of videos of the flagellum in action complete with the evolutionists using 4 letter words to describe how incredibly stupid anyone would be to believe in intelligent design and some showing - in slow detail how this could have evolved step by step. Like legos. I know how the chemicals fit together. But I also know I can sit my chemicals out on the counter in my class for Chemistry and wait until doomsday and the experiment is NOT going to happen on its own..but I digress..). But I also do not like the creationist's videos that get super excited if they know nothing about the evolution point of view (so educate yourselves). (Always be prepared to give an answer..apologia..). I had nothing to do with the creation or invention of the flagellum (ha! I bet you didn't know that) but I know Who did. And He's the only one who will ultimately be able to explain all of Creation. It's all pretty incredible.