Material explanations commonly begin with constituents: particles, molecules, cells, genes. They then treat form as a downstream result, assembled after the relevant pieces are known. A geometry-first account begins one step earlier. Before a system can execute a function, it must possess a structure capable of admitting that function.
A surface can bend in some ways and not others. A cavity supports some resonant modes and excludes the rest. A folded sheet alters distances, gradients, and paths without adding a new substance. A boundary concentrates, redirects, or disperses a field because of its shape. The geometry is not decoration laid over the mechanism. It is part of the mechanism.
This is easiest to see when the material remains the same while the form changes. Diamond and graphite are made of carbon, but their different arrangements produce radically different capacities. Fold a conductive sheet and the distribution of strain and field changes with the fold. Change the shape of a bacterial cell and its internal oscillatory pattern reorganizes to fit the new boundary. Grow one layer of a soft sheet faster than another and the surface buckles into ridges and valleys. Composition matters in every case, but composition alone does not choose the result. The admitted behavior belongs to the material-in-form.
The admission rule therefore does not replace physics, chemistry, or biology. It asks what those disciplines often leave implicit: what prior spatial and relational conditions make a given process possible?
Once that question is asked, several patterns that are usually kept apart begin to belong to one inquiry. Spirals occur in shells, chemical waves, galaxies, and the electrical activity measured across cortex. Branching appears in rivers, leaves, lightning, and electrical discharge. Periodic forms arise in sound, membranes, convection cells, and standing waves. These shapes are not inherited from one another, and their local mechanisms are not interchangeable. What they share is more fundamental and more limited: each is a member of a family of forms repeatedly admitted by different media under different conditions.
They are not the same thing. They have something in common.