The way that you will easily deduce which one it is is that you'll see the mouth first instead of the anus because of the different ways of development.
Answer:
Index fossils represents the fossils of the organisms that lived in a particular geological time zone. The index fossils defines a geological time of a dead organisms. Index fossil ensures that a correct order of geological time appears in a fossil record. The index fossils of organisms that lived for a short period, were abundant and widespread geographically.
