Definition of

Archean Eon

  1. (noun, time) the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life

via WordNet, Princeton University

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Word of the Moment

Sawdust Mushroom

an edible agaric found in piles of hardwood sawdust; the caps are black and coarsely wrinkled