What led darwin to believe that organisms originate from a common ancestor?

Charles Darwin is considered the father of evolution. The book of his is Origin of species.

The correct answer is a homologous organ.

Charles Darwin went on the voyage to travel the world, where he went to the Galapagos island and notice that the finch bird in that island has a different type of beak but the bird on other islands has a different beak but same body structure.

The size of the turtle is very different on that island.

This led to Darwin believes about the common ancestor.

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The belief that organisms originate from a common ancestor was much of the basis that the theory of natural selection was based on. Evidence of animals sharing the same characteristic, even though it appears to be of no advantage to some, appears to have been at the root of this faith. Charles Darwin was the first scientist to publish a consistent theory of natural evolution.

the food storage products of chrysophytes are oils or the polysaccharide laminarin.   formerly classified as plants, the chrysophytes contain the photosynthetic pigments chlorophyll a and c all but the yellow-green algae also contain the carotenoid pigment fucoxanthin.