Question: are the sacrum and coccyx fused?
Answer: The coccyx, commonly known as the tailbone, is below the sacrum. Individually, the sacrum and coccyx are composed of smaller bones that fuse (grow into a solid bone mass) together by age 30. The sacrum is made up of 5 fused vertebrae (S1-S5) and 3 to 5 small bones fuse creating the coccyx.