Fifty miles of color-coded pipes as thick as an arm wind along the wall. It could be the inside of a submarine or the backside of skyscraper. The territory is industrial grunge. The technosphere supports the biosphere. Huge blowers circulate the entire air of Bio2 several times in one day.
Heavy pumps move the rainwater.
The motors of the wave machine run day and night. This unabashedly manufactured world is not outside Bio2 but inside its tissue, like bone or cartilage, an integral part of the greater organism. For example, Bio2's coral reef would not have worked without an eerie backroom in the basement where the algae scrubbers hide. The scrubbers were table-wide shallow plastic trays filled with a pool of algae. The whole room was flooded with the same type of halide sunlamps as illuminated artificial coral reefs in museums.