1943 Steel Penny Cud

Not a cud because the area isn't raised (from that piece of the die falling out).
If the whole line is a crack this is referred to as a precud (before the piece of the die fell out)

One thing to look for on an authentic cud this size would be weakness of details directly opposite where a cud is located. This is because metal is forced up and out where the cud is and isn't available to fill the die details opposite the cud. Not only will details be missing but often there will be a slight depression of the field opposite a large cud.

That's what I call it.

I have only a few mint errors.
Here's a pair of 1943 cents from the same damaged die pair.
I think it is called a "progression set". Top is an earlier strike where the die has cracked from rim to rim.
Bottom is a strike after the cracked portion broke completely away from the obverse die and a portion of that coin is the same shape and location as the die crack.
When these are discovered by mint employees at the press, they change the damaged dies.
There could be earlier strikes, with incomplete cracks, (not rim to rim) and possibly later strikes than this pair with even larger "cuds".

One clue, I think I can see a die clash on the reverse. It is most visible running at an angle through the bottom of the E in ONE and runs toward the right top of the N in CENT.

I have tried to find an undamaged example of this "progression set" with that die clash, to add to the pair as a third part. (Before Die Crack)