I've noticed that at the end of each night (after the sun rises), there will occasionally be a skeleton or two left behind. These skeletons do not move at all, have no reaction to players or anything else near them, and do not burn in the sunlight. Walking into one will cause you to be pushed back as usual, and wolves will attempt to attack them. They only register one hit on them, and then won't take any damage afterwards. These "statues" will despawn after a player goes far enough away from them, as per usual.