Graphite (it's a crystalline form of carbon and used in pencils)
There was a rumour that Russian cosmonauts used pencil on their missions instead of NASA's million-dollar space pens, but I found this website says it's a myth:
The problem of weightless writing was not solved by either Soviet central planning or good old American sub-contracting, but by a private investor and a good idea
www.scientificamerican.com
When graphite is under extremely high pressure and temperatures, it can turned into diamond.
Some people think they are like graphite,
Which could be turned into a diamond.
In an attempt to outshine, they fight,
Though they know well it's a fool's errand.
I couldn't be a brilliant diamond, gee,
There is no fame or fortune for me.
It's not unfair; I know I wasn't tough,
And I know I've not tried hard enough.
But graphite writes courageous stories,
Which give you guts to face your worries.
And it draws a beautiful picture,
Which shapes our compassionate culture.
Know that you are a gem of human -
Graphite has a great role in God's plan.
(a poem by LoiteringClouds)