Bubbles generated by blowing air into a watery solution of soap generates a foam with a pattern of polygonal bubbles that may be regarded as crystallites. They are formed on the extremely thin surface film of the soapy water bubbles. The polygones may vary from seven-sided to four-sided, with six sides being most common. With time, a matter of minutes, the number of sides will decrease, and/or the bubbles will burst. These foams often display colors of iridescence on their surface.