Each concept here is mapped to its prerequisites — the ideas you'd need first to understand it — all the way down to four foundations: Space, Time, Energy, Pattern. Click any prerequisite to drill down, or scroll for the chain graph.
A mineral formation produced by mollusks, which are living organisms that have cells, interact with their environment, and possess value due to their rarity and beauty.
External reference — all senses of the word “pearl” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.