This is a real bone mounted Sacrum study. It stands 20cms tall with the ebonized wooden base measuring 11.5cms diameter. The bones are very old and have been used for a great many years as a medical study aid. The sacrum, is the large, triangular bone at the base of the spine that forms by the fusing of sacral vertebrae S1?S5 between 18 and 30 years of age. This sacrum also has the coccyx present. These are often lost and damaged. The coccyx, commonly referred to as the tailbone, is the final segment of the vertebral column in humans and apes. The coccyx is the remnant of a vestigial tail.