It is a Retain internal die break.
What is the differences between a die crack and a die break?
Note the image on the left on the back image? That is a die crack. But as the crack continues to get deeper into the die, the more the die surface crumbles, erodes away. When more of the die material breaks away and falls off the die, the more the metal goes away. When it get to a certain point, the continued striking makes a void along with the die crack. This is often seen as a ring around a certain area making if look like to us like it could break away. But keep in mint that this is developing a post and doesn't break away, but just keeps enlarging with continued use of this die. These are so common on the 1950's wheat cents that most don't give them much attention and are not a premium on this area. The more interest are on the reverse die cracks/breaks/retained
Cuds and
Cuds. I don't recall seeing one of these break away or distort the on the obverse. But you never know, someday some one will probably post one. So stay tuned in here to see if it shows up.