Possible Clues:

• Bones at the bases of spines
• Backbone parts
• Neighbors of 7-Down
• Spine-to-pelvis connectors
• Spinal bases
• Bones that form the human pelvic arch
• Pelvis connectors
• Triangular bones composed of fused vertebrae
• Bones: principal ingredients of stock as cook regularly avers
• They have to be bony at the back over the bottom