But sometimes, the hard parts of certain organisms is mineralized as part of a sedimentary rock and becomes a fossil.
(the hard parts of certain organisms; is mineralized; as part of a sedimentary rock; T:sometimes) (the hard parts of certain organisms; becomes; a fossil; T:sometimes)
the hard parts of certain organisms the hard parts of certain organisms
is mineralized becomes
as part of a sedimentary rock T:sometimes
a fossil T:sometimes