A snail grows its own home and never outgrows it but augments it as it grows.
The ovary of an apple blossom becomes the core of the apple. The blossom’s hypanthium, which connects petals, sepals, and stamens, swells in size and surrounds the core with its seeds inside.
The scroll of a violin is mere decoration. Everything else is dictated precisely for producing sequences of exact tones.
When it rains, you don’t raise an umbrella because it’s pretty.
Circle, ellipse, parabola, and hyperbola come from a plane intersecting a cone at different angles. In their appearances, they would seem to be unrelated.
The purpose of a leaf is to gather light and by photosynthesis in surface cells supply the tree with energy in return for water and nutrients supplied by veins. Attend to the patterns of veins. A tree leaf may be parallel, pinnate, arculate, dichotomous, longitudinal, palmate, rotate, cross-venulate, or reticulate. The venation of a leaf is perfectly suited to its shape.
Knowing the rule of construction a two-dimensional object becomes three-dimensional. A rectangle with a line drawn from its bottom-left corner to a right-angle branch becomes the side of a box that you are permitted to peer into.