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Now, a quick word from our our sponsors before tonight's story begins.

Hello everyone. I'm Olympia. Thank you for being here with me in this wonderful place called Lights Out Library, and I have a great story to tell

you. Three to four billion years ago when Earth was still a young planet, life forms appeared in its

primordial ocean.

For almost three billion years,

these life forms remained very small,

made of a single cell for most of this period.

But they multiplied.

They diversified and slowly changed the chemical composition of the seas. Then suddenly, about 540 million years ago, the number of marine species, their variety and their sizes

increased dramatically, in an event called the Cambrian explosion.

All sorts of creatures, mollusks, fish, crustaceans, radiated and formed more and more complex food chains.

From there, they would colonize the land and sometimes return to the sea.

This is the journey I invite you tonight.

We're going to travel in time and discover how marine life evolved,

how it appeared, or what we think we know of it. How groups of species rose to the top of their

food chains and fell,

and what happened when extinction events reshuffle the deck repeatedly?

We will discover many extinct species of spectacular sea creatures,

some of which were the largest ones to ever live on earth, from sea scorpions

...