Bones that form between sheets of fibrous connective tissue develop through ossification.

Yes, that's correct. Bones that form between sheets of fibrous connective tissue develop through a process called intramembranous ossification. Here are the steps:

1. Mesenchymal cells, which are essentially stem cells, cluster together and start to differentiate into specialized cells.

2. These cells become osteoblasts, which are bone-forming cells.

3. The osteoblasts start to secrete osteoid, a type of bone matrix, which gets mineralized within a few days.

4. As the osteoid becomes mineralized, it forms a bone matrix, or a bone spicule.

5. The bone spicule then spreads into a network of trabeculae.

6. Osteoblasts on the surface of the trabeculae continue to secrete osteoid, which increases the size of the trabeculae.

7. Eventually, some osteoblasts get trapped in the osteoid and become osteocytes, the cells that maintain the bone tissue.

8. Finally, the trabeculae become interconnected and form spongy bone.

This process is how flat bones like those of the skull and clavicle are formed.