Hopes this helps:
Answer:
The body of a fish is streamlined because, it increase the speed of the fish in the water. The more the streamlined shapes more easier for the fish to swim in the water.
I believe its is because the fossils of these animals looked like living species and they had a connection to the modern. A fossil is any preserved evidence of life from a past geological age, such as the impressions and remains of organisms embedded in stratified rocks. Fossils are created when organisms die, are in cased in dirt and rock, and are slowly replaced by minerals over time.
Almost no discernible structure
It makes all the corrode stuff deposit at the bottom if there wasn't any gravity<span />
