Diatoms!

I've been doing some reading, and unfortunately I can't find the original article I read, but diatoms seem like one of those things that could really revolutionize the way we dye things. Researchers at Oxford have found a way to use these unicellular algae to colour everything from paint to fabric. Its the crystal like structure of their shells, which give them their colour, and they are quite small - 1/3 the width of a human hair. you can find out more information here, and here. Thank you Treehugger and Wired for all of the information