It's a simultaneously beautiful and disgusting work of art. Tasha Sturm of Cabrillo College in Aptos, California sent her 8 and 1/2 year old son outside to play. When he returned, she pressed his hand into a large plate of trypticase soy agar. The bacteria on his hand grew into this lovely formation--a vibrant array of colors and fractal shapes. Sturm describes it in more detail in the comments at this post.