2. How have fossils been preserved over millions of years?

A fossil is the remains or traces of a once-living plant or animal that was preserved in rock or other material before the beginning of recorded history. ... Fossils of single-celled organisms have been recovered from rocks as old as 3.5 billion years. Animal fossils first appear in rocks dating back about 1 billion years.

Explanation:

Five

Five types of fossils: (a) insect preserved in amber, (b) petrified wood (permineralization), (c) cast and mold of a clam shell, (d) pyritized ammonite, and (e) compression fossil of a fern.

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. those muscles push materials like food or blood through organs. unlike skeletal muscle, smooth muscle can never be under your control.