Historical clue formulations

• Tundras and deserts, e.g. — 2025-10-08
• Savanna and tundra — 2022-06-04
• Wetlands and tundra, e.g. — 2016-05-03
• Rain forests and grasslands, e.g. — 2007-12-30
• Ecological units — 2005-12-04
• Some complex communities — 2003-10-11