Although some would argue that this is a Biology problem, I would like to read some views from physicists regarding the following problem: Amoebas have no muscles nor cilia (microscopic, "paddling" hairs). Yet they are highly mobile. They move about by pushing protuberances, called pseudopodia, out in the desired direction of movement, and then flowing the remainder of their innards into the protuberance. The riddle is, how do they pull this off without any internal muscles or known pumps, etc.? There is lots of info on the Internet; yet I haven't read any satisfactory PHYSICAL explanation of the phenomenon.