A story from CBC Radio Quirks&Quarks program about the giant clam (Calyptogena magnifica) that practically outsources the energy production function to a bacteria.
It seems the bacteria produce all of the nutrients the clam needs to survive in this inhospitable environment. The clams, in turn, give the bacteria a safe place to live and a constant supply of sulphur, which they need in order to produce their own energy supply.http://www.cbc.ca/quirks/archives/06-07/feb24.html#2
