hells angels

An episode of Journey to the Microcosmos, hosted by Hank Green, about diatoms, single-celled algae with glass shells. It covers their role in producing a large share of Earth's oxygen and their uses in beer filtering, paint and kitty litter.

Isaac Arthur explains the Matrioshka Brain, a hypothetical computer or artificial mind powered by an entire star using nested shells. It covers how such megastructures relate to Dyson spheres and superintelligence.