Is a “soul fragment” like a block of marble that got knocked off and was left behind (compared to a pile of sand)?

The soul fragment is a packet of energy with an individual signature, so it, in a sense, can be thought of as being analogous to a block of marble or a particle of sand. The reality here is that both physical objects are part of a larger whole. It is only a question of the yardstick you choose to use. So if the block of marble is part of a great mountain, it is only a difference in scale to compare that to the grain of sand compared to the pile. The fact that it is fragmented compared to the mountain is only a condition of existence and not that mountains always must be fully integrated and never divided over geologic time. Mountains do come and go. So the matter does not disappear, it changes shape and will move about, subject to forces of wind and water and the Earth upheavals that may occur. But the condition in a particular point of time is dependent on history and local conditions both. The analogy you make is accurate up to a point, but the energies are so vastly different and the potential reach of the soul being vastly greater than stone, we would not use this analogy. The stone knows where it is, what it is for, but it is essentially static in the reach of its consciousness. It can look out and it can do some interconnection with consciousness elsewhere, but its reach is not unlimited. The reach of the soul is unlimited. This is what gives the soul fragment great power to be a mechanism for karma and its expression. The soul fragments travel across time and will be drawn once again to the reincarnated being and will represent a karmic destiny. This is a high-level function of consciousness, to carry out such a role. So the intricacy and the inherent capabilities of the soul fragment versus energy in a material form are vastly different. The spirit meddlers cannot harvest soul fragments and use them as energy. They can only use the energy generated by the consciousness of a living person or a living organism. The consciousness of the material world is of little value for them. They seek first of all, human-level consciousness, as this is what they truly need for long-term survival. They will turn to animals and plants as secondary and tertiary choices, but have great difficulty maintaining a minimum threshold of energy. And if they cannot summon sufficient energy to engage with and invade a human target, all will be lost for them. So it is the extremely debilitated spirits who end up subsisting on plant life and it is an end-stage for them in meeting the ultimate fate.