Polygons

Polygons are passive shapes that give experience when destroyed. They can range from the tiny Egg that is smaller than a lvl 1 tank to the massive Golden Icosagon, twice the size of a mothership. There are Green and Orange variants of simple shapes. Simple shapes have dedicated sanctuaries, which spawn a boss when killed.

List
Some shapes have estimates for experience or health.

Evolution
Shapes start their life as an egg. If they are not destroyed prematurely, they can "hatch" into a square, and then evolve over time into triangles, pentagons, and so forth. After Beta Pentagon it takes much longer to upgrade. They evolve according to this tree.

This tree may not be fully accurate.

fun fact - shapes can spawn as orange or green variants, and beta pentagons can spawn by themselves or as a green variant, without upgrading from a pentagon, it is just rarer for this to happen.