O_O (that's my shocked face) - the Galaxy S5 has a heart rate
  monitor built in? Makes sense - the device is for humans and
  humans like to know their heart-rate. I can imagine a future
  device sticking a blood checker - it wouldn't be hard to put a
  spot for diabetes testing strip in it, or other things that can
  be tested by a drop of blood and if you think i'm making fun of
  the extra feature, I'm not! I'm thinking 10+ yrs down the road.
  Also, the water-resisant of the galaxy to 3 feet down is a BIT
  plus: All smartphones should be water-proof - there's no excuse
  for that in 2014. "