In which bones can bone marrow chiefly be found? Is bone marrow made of bone tissue?

Explanation

### Step-by-Step Solution:

1. **Understanding Bone Marrow**: Bone marrow is a soft, spongy tissue found within the cavities of certain bones. It plays a crucial role in producing blood cells.

2. **Identifying Locations of Bone Marrow**: Bone marrow is chiefly found in the internal cavities of:
- Flat bones (e.g., the sternum, shoulder blades)
- Irregular bones (e.g., vertebrae)
- Long bones (e.g., the hips)
...