Live rust?

Hi,
I'm wondering what the deal is with live rust. I heard that rust is
sometimes caused or catalyzed by basically a bacterium or perhaps more
primitive life form that is basically some of the non-organic bacteria,
primitive metallic life.
The other day I was digging holes in the ground, and there are these
rocks there. They're crumbly, they split open and fall apart when
they're speared with a twenty pound pointed iron bar. They have this
rich orange rust growing in them. So anyways it was muddy and some of
the mud splashed on the bar. Only a few days later, there were rust
spots on the bar that were growing.
I figure if I want to remove rust from these things I use phosphoric
acid, naval jelly, to remove the rust and brush, wipe, and paint over
with primer, or powder coat, but I'm more interested in the biological
(?) catalysts of rust.
Is that totally mistaken? There was definitely more rust after
exposure to live rust than there was before that. If they're bacteria,
they aren't necesarily non-organic, or not cellular organisms, or are
they? Rust bacterium here is just a name for what wee metallic beastie
causes rust.
Thanks,
Ross F.