Click the flag. Very simple rules generate a pattern seen on certain kinds of sea shells. Before clicking the flag, you can click the left button to choose fractal triangles or shell pattern. Fractal triangles alters the shell pattern rule very slightly to produce a fractal known as Sierpinski's Triangle. You can also choose to start with one point or four points in the first row. Choose before clicking the green flag. Each new row follows a simple change rule. Each row is permanent, but the next row is a variant of the previous. This is a space-time map or diagram. (We include a sea-shell with similar patterns in our Discovery Box, along with drawing exercises and code variants).
Chris Keane of Flock Ecogames wrote this program as part of a Discovery Box on spots and stripes on shells and lizards. See: lifepatternsemerging.com Creates a row of square clones. One square is red. Then the row "stamps" its color onto the backdrop. Then the row of square clones moves down a row and follows a simple rule of change. The rules are known as elementary cellular automata rule 90 (creates the Sierpinski's Triangle, or eca rule 18 (creates the shell pattern).
