Historical clue formulations

• Spiral-shelled mollusk — 2024-03-11
• Large seashell — 2021-10-11
• Seashore souvenir — 2015-01-15
• Beach souvenir — 2010-12-03
• Shore souvenir — 1999-07-25
• Spiral shell — 1998-11-22
• Shell — 1997-09-07