This structure, conceived in 1974 to drift at 3 000 - 4 000 meters depths and allowing the observation of Mid-Atlantic Ridge is a mobile laboratory in deep water. Autonomous for a period from 1 to 3 months and capable to host 12-15 people, this underwater habitat with research and service areas was made of metallic spheres. A semi-rigid outer frame assured the protection of the vessel. A true bionic medusa, Pulmo is an ultimate example of a perfect transition from a living form to a constructed one.