Answer:
Salt, in chemistry, substance produced by the reaction of an acid with a base. A salt consists of the positive ion (cation) of a base and the negative ion (anion) of an acid. The reaction between an acid and a base is called a neutralization reaction.
Explanation:
The deeper you go down in to the rock the older the fossils get. So when the scientists go in to the rock they can say what animals lived in that time and what animal was the oldest.
The example of an baryonic material is dark matter I hope this help