Low confidence estimate: this is a sea surface/lower atmosphere monitoring station. It is hollow. It has electronic components, but its power supply has failed.
Structure age: two hundred years (inferred from weathering of antennae).
Composition: single cast titanium-palladium alloy, probably manufactured by the Kroll process.
Instruments: passive sonar, plankton scanning sonar, proton magnetometer, Doppler radar and current profiler, wave height gauge, conductivity/temperature rosette sampler, sediment traps, plankton photo booth, ASIMET air-sea energy transfer sensor, lidar atmosphere sensor, hyperspectral imager, wind speed/direction log, cloud imaging radar, etc. They are nonfunctional.
Power supply: a nuclear battery, either thermal or alphavoltaic. The plutonium in the battery continues to emit, but no power is being generated. There is wiring for a secondary power source but the generation technology is unclear (possibly microbial fuel cells).
Induction: the builders of this sphere were significantly more advanced than those who built the anchoring tower. Evidence of rapid technological progress.
This station was designed to float at the water surface and to communicate with other stations by radio aerial. Some of the communication equipment suggests the presence of a satellite network overhead.
Induction: the sphere was built by an early digital civilization comparable to Earth’s Information Age.