You can get pyramids with different shaped bases. Triangles, pentagons, hexagons, any shape. And a circle becomes a sphere with just one large, curved face, like a ball. Perfect for, uh ...
Polygons are multi-sided shapes with different properties. Shapes have symmetrical properties and some can tessellate. Loci and constructions - Edexcel Loci are a set of points with the same property.