What is the missing piece (marked "?") in this configuration of a normal chess game?

BLACK

WHITE
Notice that the Black King is in check by the White Rook.

(In reply to An impossible check?? by brianjn)

Very good observation, brianjn.  The king could not have moved into that position.  Standard chess rules makes such a move illegal.  There must have been an intervening piece that is no longer intervening. 

Yet, consider the piece that had been moved to create the discovered check IS still on the board.  It just graduated into a new position with a new form and ability. 

Posted by Dej Mar on 2008-06-12 11:43:33