It's an unassuming rock, greenish in colour, and just over 4cm in its longest dimension. And yet this little piece of sandstone holds important clues to all our futures.
It was recovered from muds in the deep ocean, far off the coast of modern-day West Antarctica.
The scientists who found it say it shouldn't really have been there.
It's what's called a dropstone, a piece of ice-rafted debris.

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