Looks like it could be a pre-cud. Look here: Lincoln Cent Pre Cuds; 1955 : Cuds on Coins (cuds-on-coins.com)
Looks like possible splatter of some kind. Look at the spots around the area in question. In either case, NAV, IMHO.
Rim to rim die crack with chipping, could could very definitely eventually develop into a retained or full cud.