An unstruck split cent planchet somehow made it into the striking chamber with another complete, normal cent planchet. It was completely in the collar with this other normal planchet, with the split planchet being in between the reverse die and the other planchet. The dies struck and left this coin with a direct obverse strike, while then other shows the textured split half being rammed into it. The split planchet was thin enough that some reverse designs transferred, albeit weakly with just enough of a pattern to make out the Memorial with some fuzzy lettering. Thus, this is a "(reverse) struck through a split planchet" error. Weighs the proper weight as this error type should. Very rare but affordable as demand isn't too great, but very cool.