Historical clue formulations

• Ecological community — 2025-10-10
• Tundra or taiga — 2025-07-27
• Desert or tundra — 2024-07-15
• Desert or tundra — 2023-07-19
• Tundra or savanna — 2022-04-10
• Tundra, e.g. — 2020-10-10
• Forest, e.g. — 2020-04-11
• Community of plant and animal life — 2010-05-25
• Major ecological community — 2009-03-01
• Tundra or rain forest — 2006-12-16
• Community of plant and animal life — 2003-07-05
• Ecological community — 2001-02-14
• Ecological community — 2001-02-04
• Complex ecologic community — 1998-03-14