At one time, the president who had retreated and retreated until he was pressed against the wall, could only be secured by a number of gentlemen forming round him and making a kind of barrier of their own bodies.

VOA: special.2009.01.19

And this dimple is later forming a vesicle, a round ball, that goes on and forms the ear.

随后形成一个圆球状的泡囊，直至发育成耳朵。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选