It's hard to think of anything crucial to us human beings that doesn't involve oxygen. Not just the air we breathe and the water we drink but we find it in literally every protein that makes up our bodies and every bite we eat. Oxygen is life itself!
A little ampule containing a little of this life-giving O2 in pure form.
Comes in two varieties: regular and a special, low pressure gas ampule which will glow when ionized under high voltage. See colors at bottom of elements page