Well they say "Solein, protein out of thin air, is not a plant nor an animal. It originates from a natural, non-modified, single-cell organism" so my guess is t

Well they say "Solein, protein out of thin air, is not a plant nor an animal. It originates from a natural, non-modified, single-cell organism" so my guess is that the specific micro-organism is a trade secret to protect their business, not because it's like, people. But you could always email them to ask. Maybe it is people.