In a chemical reaction, the atoms and molecules that interact with each other are called reactants. No new atoms are created, and no atoms are destroyed. reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.
They can use 3d printers to make identical copies of things such as fossils. The reason why that is useful is because REAL fossils are rare. So they can still study the traits and characteristics of the fossils without having to buy a fossil or find one because they are rare and they cost a lot