"Stereocilia" are nothing more than long, filamentous microvilli, and they most certainly aren't "cilia" in any sense of the word. They have NO axoneme and they are NOT capable of movement. The misleading term arose in the days before the electron microscope, when their great size (they're much larger than ordinary microvilli) led people to conclude they must be a form of cilia. This is now known to be completely false, thanks to EM investigations.