Cracking the Secrets of Old Faithful's Geyser Eggs

Researchers get their first look at a geological 'gobstopper' from Yellowstone, which may hold clues about its iconic geyser's past and future.

The animal kingdom brims with egg-laying creatures—chicken, goldfish, toads, and more. But one thing you might not expect to lay an egg is a geyser.

Geyser eggs don't spawn a swarm of baby steam-sputtering structures; they are, after all, rocks. But they're far from ordinary: These pebbles are like geologic gobstoppers. They solidify layer by layer as silica from the steamy waters of geothermal pools precipitate out of solution, making each layer a snapshot of pool conditions at the time it was formed.

A trove of these geologic oddities lies scattered in the colorful thermal pools surrounding Yellowstone's Old Faithful geyser, yet strong protections within the national park have long prevented scientists from getting their hands on the eggs. But

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