Today I heard from my friend "Э оборотное". I still do not understand why he called it "оборотное". Is there a secret letter "э", which only Russian native speakers know about, which is turned the other way, or could it be written both ways? Maybe, even, there was a reversed letter "э" in old Russian? I am not sure, since the only thing I get in Google, when I type in "э оборотное", are articles about the normal letter "э".