Historical clue formulations

• Shape-shifting seat — 2021-06-29
• Piece of equipment in the game cornhole — 2019-04-13
• Casual type of chair — 2014-03-11
• Midway missile — 2014-01-03
• Squishy seat — 2013-09-15
• Ashtray base, perhaps — 2011-11-26
• Noisy but comfy chair — 2009-07-12
• Hacky Sack, basically — 2009-03-02
• Nontraditional chair style — 2007-10-08