I remember watching a film on TV that involved astronauts going to a planet, which might have been Mars. It had some sort of life form that were described as "breathing bags". They were attached to cave walls and seemed to breath in and out. I remember it being very creepy and the image has stayed with me all these years. I think it was a movie - but I could be wrong. If it was a movie I probably would have seen it again as these sort of things tend to turn up again with time. I was very young at the time - and quite old now. I saw this in probably the early to mid seventies. So this could be something from the 60s or 50s. I don't think it was something like the Outer Limits or Twilight Zone as I wouldn't have been allowed to see it. But now I think of it - I think it may have been, and I managed to steal a look at it. Any ideas?