To illustrate what I meant by such causes of form:
When a set of soap bubbles are brought into contact with one another and partially join in the formation of a common structure, the ADAPTATIVE sharing of finite space, matter, and energy helps to originate that generic shape we call foam.
The form of some plant stems is caused by the biphasic 180 deg ALTERNATION of small branches along its length.
The ATTRACTION of charged particles in the solar wind by Earth's magnetic field plays the key role in inducing the intricate shapes and transformations of the aurorae.
From the INTERFERENCE of vibrations in the bodies of musical instruments emerges elegant and unexpected shapes, which impress themselves upon sounds as timbres rich with esthetic potentialities.
Although it is essential to distinguish and classify the range of types of forms, it is even more important to investigate and characterize the general principles and phenomena which are the SOURCE of shape or the DETERMINANTS OF ITS CHANGE, EVOLUTION, AND BEHAVIOR. We must discover not only WHAT forms exist but WHY and HOW they exist - why the world or its things have the shape they do or, indeed, have any shape at all.
Do not make the mistake of assuming that because questions like these
are so elementary they must already have been answered. In fact, it is
usually the simplest things that we are most ignorant of.