Bacteria Lite Brite
It’s not every day you see a painting swarming with bacteria; or in this case, a painting made with bacteria: (via Wikipedia)

It’s a painting of a beach by Roger Tsien’s lab. They inserted differently “colored” fluorescent proteins into a bunch of bacteria, and then “drew” the picture with toothpicks that had been dragged through the colonies of those bacteria. Since it’s a little hard to see exactly what you’re doing on a semi-transparent gel (which is what the picture was drawn on), this is actually not that easy to draw!
Reminds me of Lite Brite. Anyone else have those as a kid?