This means that oil was formed by bacteria acting on the remains of tiny organisms (fossils) in the ground that lived millions 
(bacteria; acting; on the remains of tiny organisms (fossils) in the ground) (the ground; lived; millions) (This; means; that oil was formed by bacteria) Context(This means,List([0, 10))):(oil; was formed; by bacteria)
This means,List([0, 10))
bacteria the ground This oil
acting lived means was formed
on the remains of tiny organisms (fossils) in the ground
millions
that oil was formed by bacteria
by bacteria