Block D "Crasher" stage .
. This is the only photo I've been able to find of the Block D "Crasher" stage which would have served to decelerate the LK lander out of lunar orbit and then slow it down before it was finally jettisoned at ~2 km over the lunar landing site. At that point, the LK's own engines would have taken over and lowered the vehicle down to lunar touch down.
