Inflexible Tessellation

Regular pentagons
Can never tile a plane.

Only triangles, squares,
And hexagons manage.

Nor can any convex
Polygon of more than

Six sides wholly tile planes.
Convex hexagons draw

The line for sides that can.
Aperiodic tiles,

Of course, are their own thing,
Limit at the small end,

Monotile, hat tile, one
Stone, ein Stein, true spectre

Tile without reflection.