Pieces of steel in cylinder??

The seat would hula hoop on the valve and would need to break apart to leave the valve and begin its crushing between the pistons and head. Now if it hung to one side the piston 'could' then hit the valve and seat and at that point it would also crack apart. Yes it can go through the intake into the other cylinders, I lost a piston if you all remember and it went into all other cylinders by means of the intake manifold.

I noticed the sunk valve and thought along the same as George.