Corpse Girl’s skin tissue / nanites

She hit a key and called up another picture. In this one dozens of webs were stretched out long and thin. The arms were gathered in parallel bundles. “These are from a tissue sample we took. Hundreds of them linked together to form bone muscle fibers…
These things reshape themselves to mimic different cells, depending on where in the body they are. Blood cells, muscle cells, skin cells. They can even work together to imitate nerve cells…”
St. George tipped his head at the microscope image. “So these are in Maddy? They have something to do with her … condition?”
“They’re not in her, George,” Connolly said. “It’s all she is.”

Excerpt From Ex-Communication, pg 439
Peter Clines
https://books.apple.com/us/book/ex-communication/id635706546