Water + Water = Lake
Lake + Water = Ocean
Earth + Earth = Mountain
Mountain + Earth = Volcano
Volcano + Ocean = Island
Island + Island = Continent
Continent + Continent = Planet
Planet + Fire = Sun
Sun + Planet = Solar System
Solar System + Galaxy = Universe
Earth + Water = Plant
Plant + Time = Tree
Tree + Tree = Forest
Forest + Human = Civilization
Earth + Fire = Lava
Lava + Water = Stone
Stone + Fire = Metal
Metal + Human = Tool
Tool + Human = Worker
Worker + Life = Human