But most importantly of all, it allowed me to get Godwin’s Law into Nature (3rd paragraph from bottom). Thanks Meredith L Patterson!

From the piece (do read the full one):

For millennia, people have written secret messages in invisible ink, which could only be read under certain lights or after developing with certain chemicals. Now, scientists have come up with a way of encoding messages in the colours of glowing bacteria.

The technique, dubbed steganography by printed arrays of microbes (SPAM), creates messages that can be sent through the post, unlocked with antibiotics and deciphered using simple equipment.

Manuel Palacios, a chemist at Tufts University in Medford Massachusetts, [encrypted] messages using seven strains of Escherichia coli bacteria. Each one was engineered to produce