Polygons

Polygons are passive shapes that give experience when destroyed. They can range from the tiny Egg to the massive Golden Icosagon. There are Green and Orange variants of simple shapes. Simple shapes have dedicated sanctuaries, which spawn a boss when killed. This list doesn't include Mega Sanctuary and its spawned polygons / the normal versions of Alpha shapes and Golden Icosagon.

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. Golden Nonagons and Golden Icosagons are not in the evolution tree, as the Golden Nonagon only spawns from the death of a Golden Sanctuary and Golden Icosagons only come from the evolution of a Golden Nonagon.
 * Egg
 * Square
 * Green Square
 * Orange Square
 * Orange Triangle
 * Orange Pentagon
 * Green Triangle
 * Green Pentagon
 * Green Beta Pentagon
 * Splitter Square
 * Super Splitter Square
 * Splitter Pentagon
 * Splitter Hexagon
 * Splitter Decagon
 * Summoner Square
 * Triangle
 * Pentagon
 * Green Triangle
 * Green Pentagon
 * Green Beta Pentagon
 * Orange Pentagon
 * Orange Triangle
 * Orange Pentagon
 * Tri-Blade
 * Poison Tri-Blade
 * Deltrablade Lite (rare)
 * Red Runner (Tier 2)
 * Red Runner (Tier 3)
 * Red Runner (Tier 4)
 * Pentagon
 * Green Pentagon
 * Orange Pentagon
 * Green Beta Pentagon
 * Beta Pentagon
 * Green Beta Pentagon
 * Alpha Pentagon
 * Alpha Hexagon
 * Alpha Heptagon
 * Alpha Octagon
 * Alpha Nonagon
 * Alpha Decagon