The calico scallop is an index fossil. it is well documented to have lived 1.8 million years ago. therefore, the approximate age of the rock in which this fossil is found is

Answer

at least 1.8 million years

Explanation

Index Fossils are remains of species that lived on the Earth for a relatively short time. They were abundant and widespread geographically and geologists use them to assign ages of rock layers. For example if fossils of a dinosaur are discovered in a rock layer, the assumptions is that the rocks are at least 65 million years old.

c

explanation: