A transformation occurs in many ancient stories. While Apollo is hunting the nymph Daphne, she appeals to her river-god father for assistance, and he saves her by turning her into a laurel tree. The goddess Athena transforms the magnificent weaver Arachne into a spider that spins only lovely webs out of rage and envy. Natural substances, on the other hand, can metamorphose or undergo transformation. Thousands of years of heat and pressure might convert microscopic creatures into petroleum and coal into diamonds. The change of caterpillars into butterflies is probably the most popular natural metamorphosis (see how this plural is created). Read more details here.