The Tri-spine Horseshoe Crab (Tachypleus tridentatus) is one of four living horseshoe crab species (probably, marginally, the biggest). Animals that have survived, superficially very little changed, for hundreds of millions of years. They've come through multiple mass extinctions, but are still facing new and unexpected challenges today ...

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Music

Opening & Closing Themes: Running Waters and Acoustic Meditation by Audionautix (Jason Shaw), from audionautix.com. CC BY 3.0.

Modified versions of: Modum by Kai Engel, CC BY 3.0, Another Version of You and An Extraordinary Camera Was Custom Built and Used Only Once by Chris Zabriskie, CC BY 3.0