The answer is 'Cambrian' explosion. This took place approximately 541 million years ago. 'Explosion' refers to the evolution of a large range of new major animal phyla. Scientists know this by the large number of diverse fossils from this period. Prior to this period, organisms were single-celled, but over the Cambrian Explosion, lasting about 80 million years, life forms diversified rapidly to resemble the life forms existing today.
I would assume osmosis, as sodium chloride is just salt and salt travels to water, which is abundant in the egg.
During this phase, the cell makes a variety of proteins that are required for DNA replication.
A good topic idea that could be used can be about ecosystems. Such as how geographic area, plants, animals, weather and landscape make up the types of organisms in that specific ecosystem.
