How far back does the fossil record extend? a.1 billion years b.560 million years c.3 million years d.3.5 billion years

It is D. 3.5 billion years. The "stromatolites" are the earliest fossils that have been found.

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.