Historical clue formulations

• It protects the heart — 2026-01-04
• Protector of the heart — 2018-10-05
• Expander during inhalation — 2014-11-23
• Part of a chest — 2014-04-03
• Skeleton section — 2013-01-13
• Protective part of a trunk — 2011-10-11
• Chest protector — 2008-05-26
• What a hook might connect to? — 2005-05-01
• Thoracic structure — 2002-11-10