Question: does a turtle's shell grow with them

Answer: Yes, The carapacial ridge has been found to play an essential role in the development of the turtle shell. Embryological analyses show that the carapacial ridge initiates the formation of the turtle shell. It causes axial arrest which causes the ribs to be dorsalized, the shoulder girdle to be rearranged and encapsulated in the rib cage, and the carapace to develop. O. semitestacea presents evidence of axial arrest that is observed in embryos but lacks fan-shaped ribs and a carapace. This suggests that the primitive carapacial ridge functioned differently and must have gained the function of mediating the ribs and carapace development later.