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Scientists Are Obsessed With This Lake

A TED-Ed lesson by Nicola Storelli and Daniele Zanzi on Lake Cadagno — a rare 'meromictic' lake in the Swiss Alps whose oxygen-free bottom layer is a living window into Earth's ancient past.

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  • At the end there's a 3-question test. Score 60% or more to complete the lesson, and 80% or more to master it. You can always watch again and try for a higher score.