Which of the following characteristics are necessary for a fossil to be a good index fossil? (Choose all that apply) had a broad geographic distribution
easy to identify at the species level
an invertebrate
short-lived

A good index fossil is one with four characteristics: it is distinctive, widespread, abundant, and limited in geologic time. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms.

Explanation:

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.