Basically, the concept is anomalous silkworms that have humanoid cocoons. These cocoons are in human size and virtually similar to human (beautiful girls in particular), including the ability to think, speak and move. If they get boiled and processed before the moth within them emerge, then they can be preserved as a doll. Otherwise, they still "expire" after the moth emerge, and the bodies will decay rapidly.
Now I need to flesh out the concept with some details, but I am not sure if they are good.
- How long will it take from the cocoon's formation to the moth's emergence? Not determined yet. Maybe sixteen moths or sixteen years. If it's sixteen months, then the cocoon will be in the shape of a young girl, or if it's sixteen years, the cocoon might be in the shape of an infant at the beginning and slowly grow into a young girl. Not sure which one is better.
- Where the cocoon's knowledge and personality comes from? I currently have some options in my mind, but basically it depends on the cocoon's lifespan. If it's sixteen years, they can just learn as normal humans. If it's sixteen months, I think either they learn much faster than ordinary human or they might inherit their memories and personalities from something else.
- How many silkworms will it take to form a humanoid cocoon? I prefer that the silkworms are in the size of normal ones, and many silkworms form a cocoon together. The reason is that I think that countless moths flying out from a girl's body can be an amazing picture.
- background story: These silkworms were kept secretly by a family. Before the Foundation took over these worms, there were two brothers of that family taking care of these silkworms (and cocoons). The younger brother was a medical doctor and tried many method to extend the cocoon's lifespan. Some of these methods are even inhuman. But he did really love these cocoons or at least one of them, so he kept conducting experiments. The elder brother killed the younger and told the Foundation things about these worms. (I haven't determined why the elder brother did this.)
Please let me know if you feel these details are good or bad, or have any further idea about this concept.