Why didn't life form on the moon?

Who says it didn't?

MM-eh - Who says it didn't?
Good point.

the moon is a piece of earth blown off by a meteor

Too small and uniform to have any geothermal shit happen that could have led to an atmosphere. Final answer

Never heard of the man on the moon eh?

The not having an atmosphere to shield the surface from radiation and baretolt rays probably figures in there somewhere

There isn't a life form in all of the universe that could live on nothing but cheese.  If there was, it would die of constipation.