Historical clue formulations

• It connects to the tailbone — 2025-07-03
• Bone at the base of the spine — 2023-05-07
• Hipbone attachment — 2010-08-15
• Pelvis part — 2010-01-13
• Pelvic bone — 2008-12-25
• Pelvic bone — 2008-06-28
• Backbone part — 2006-02-18
• Part of the backbone — 2001-10-02