Answer:
I am the kind of ant that's good at math.
I am round. I have only one line. Circle is not my name indeed. What am I?
I am owned by every man, though my length differs. Their wives use me after getting married. What am I?
I stand in one place yet I fill a whole room. I can be filled with molten rock and come in every hue.
I have thirteen hearts but no body or soul. What am I?
The virgin gave birth to a child and threw away the blanket.