Historical clue formulations

• Opening in a pet carrier — 2023-11-28
• Opening in a pet carrier — 2019-10-22
• Site for a seal, maybe — 2009-11-27
• Breathing aid — 2006-11-03
• Pet carrier feature — 2003-08-30
• Pet carrier feature — 1998-11-04
• Breathing aid — 1997-06-22
• Pet-carrier feature — 1997-03-28
• Opening in the ice — 1995-02-15