Historical clue formulations

• Basketball's quadruple double, e.g — 2025-03-21
• Uncommon thing — 2025-01-13
• Hole-in-one, e.g. — 2004-07-09
• Blue moon, e.g. — 2003-09-08
• Hen's tooth, e.g. — 1999-11-15
• Blue moon, e.g. — 1999-01-25
• Curio — 1996-05-09
• Thinness — 1994-06-26
• Hen's tooth, e.g. — 1994-06-12