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 Burnt 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. 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
 * Burnt Square
 * Burnt Triangle
 * Burnt Pentagon
 * Burnt Beta Pentagon (unconfirmed)
 * Green Triangle
 * Green Pentagon
 * Green Beta Pentagon
 * Splitter Square
 * Super Splitter Square
 * Splitter Triangle
 * Splitter Pentagon
 * Splitter Hexagon
 * Splitter Decagon
 * Summoner Square
 * Triangle
 * Green Triangle
 * Green Pentagon
 * Green Beta Pentagon
 * Burnt Pentagon
 * Burnt Triangle
 * Burnt Pentagon
 * Triblade
 * Poison Triblade
 * Golden Tetrablade (rare)
 * Deltrablade Lite (rare)
 * Red Runner (Tier 2)
 * Red Runner (Tier 3)
 * Red Runner (Tier 4)
 * Pentagon
 * Green Pentagon
 * Burnt Pentagon
 * Green Beta Pentagon
 * Beta Pentagon
 * Green Beta Pentagon
 * Alpha Pentagon
 * Alpha Hexagon
 * Alpha Heptagon
 * Alpha Octagon
 * Alpha Nonagon
 * Alpha Decagon