The best replacement for lungs is gills.

The best alternatives to lungs are rated as following:
★★★★★  gills
★★★  healthy lungs
★★★  smokers lungs
★★  ceremonials
★  non smokers lungs
★  smoking lungs
★  brain
★  non smoking lungs
★  healthy lung
★  bad lungs
★  non smokers
★  smoker lungs
  brain which weighs more
  cigarette lungs
  cancer lungs
  normal lungs
  brain heavier

Your alternative for lungs is not listed? Suggest!
Speaking about lungs, one probably shouldn't forget about fluid.

Other search terms related to lungs and their ratings are:
★★★★★ fluid
You have in mind a companion for lungs and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of lungs in all years. Click on graph for more.
lungs
gills
healthy lungs