It's a Spike Head, the nickname given to a die crack from the rim into any portion of the bust’s head. It shall be limited to die cracks found on the obverse of the coin. http://cuds-on-coins.com/lincoln-cent-spike-heads-1950-1959/
Is there also a lamination going on there? I see a little upturned metal at the base of the crack along with a type of square piece below it.
I was wondering what was myself I thought it was part of the crack but havnt found any similar examples