Index fossils<span> can be </span>used<span> to help determine the relative age of </span>rock<span> layers. </span>Index fossils<span> are from species that only existed for a short time. </span>Index fossils<span> are found in</span>rock<span> layers. Trilobites and Graptolites are </span><span>index fossils.</span>
<span>A dim white dwarf star, this is a star with a similar mass to earth. This star has no further fusion reactions at it's core. After this type of star has used up all of it's energy it will become a black dwarf star. Usually they are composed of oxygen and carbon. Sirius a and b are both white dwarf stars that orbit each other.</span>
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