A common remnant of life found in many areas from a specific time; this is used to help identify the age of rock layers and for relative dating.​

The answer to the question is gold

Historians are researchers of the past or people who understand the history of people. with this field, they must possess qualities such as being unbiased, patient, efficient reader, has a knack for logic and critical thinking and reasoning, disciplined, open-minded, resourceful, with good analytical ability, good reasoning skills and problem solving!