The "brain" of the colony is located in the head of the doll, inside a metal casing to protect it, and it sends signals throughout the rest of the colony to do specific things like move it's arms and legs and stuff! Under the fabric is a metal skeleton with strands of the cocoon type of fluff under the wooden arm and leg casings that it tenses and relaxes to move, and it's a bit stronger than a normal person, but a little slower. It's midsection, neck, and face are still soft and squeezable though, but if you squeeze enough you'd be able to feel the metal frame.

And if the fluff is unclear, it basically just bites off tiny pieces of food and makes more fluff out of what it bites off, which immediately starts biting off new pieces to make new fluff! So it just converts food directly to fluffyness! Tougher material like shells/bones/fur isn't converted though, and gets bunched up with old fluff and spit out as little fluff balls. The fluff that it spits out isn't dangerous and can be picked up just fine without it eating at skin and stuff.