Good morfnoevight All! EO'n'Dabs.
Those are not that big, use a winch of some type, a cable jack should be enough, use some 4x4 to make a slide out of the hole. If one weighs to much to move like that then use the old Rock'n'Roll method roll the rock to one side of the hole and back fill the other side to just where you can roll the rock up on it using dirt from building a ramp into the hole, now back fill the other side of the hole. Go back and forth until the rock has risen to the level of the ramp. now roll it out. If it is to big for that then make a bench out of it in the grow space
How many and which vertebrae got cement?