This is the hardest riddle I've ever created so far. If you can solve it I'd say you're really good. Here goes...

Half of a common germ,
Half of a yellow food.
Half of a longer month,
Half of a plane of wood.

This thing has two halves too,
One half as heavy as the other.
Tis' an object used to
Part one's life asunder.

What on earth am I talking about?