apologies for not posting for 2 weeks. i just came back from a road trip where i took these photos of the beach and coral reef in Biosphere 2, which used to be a completely air-tight terrarium of simulated worlds like a rain forest and a desert. after you've gone thru their tour, you'll understand why they charge $20. one of the many things i learned from the tour is that their energy bill for the first year that it was in full experimental operation (when the 8 scientists locked themselves in there for 2 years) was in the billions of dollars. thus they created their own energy plant. it has quite an interesting history. you can read about its story here.