A turmite is a set of rules for moving a cell on a grid. Turmites are also called turning machines or 2D Turing machines. The simplest turmite, known as Langton's ant, starts on an infinite grid of white squares. Each time the ant moves off a square, the color changes (white to black or vice versa). Whenever the ant lands on a black square, it turns right. Whenever the ant lands on a white square, it turns left. This simple rule and its generalizations lead to amazing patterns.